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Full text of "Meteorological features during Phase I of the Coordinated Eastern Arctic Experiment (CEAREX) from 17 September 1988 to 7 January 1989."

NAVAL POSTGRADUATE SCHOOL 

Monterey , California 




THESIS 



7 



METEOROLOGICAL FEATURES DURING PHASE I 

OF THE COORDINATED EASTERN ARCTIC 

EXPERIMENT (CEAREX) FROM 17 SEPTEMBER 

1988 TO 7 JANUARY 1989 



bv 



Stephanie W. Hamilton 
March 1991 



Co-Advisor 
Co-Advisor 



Kenneth L. Davidson 
Carlyle II. Wash 



Approved for public release; distribution is unlimited. 



T25468 






Unclassified 



security classification of this page 



REPORT DOCUMENTATION PAGE 



la Report Security Classification Unclassified 



lb Restrictive Markings 



2a Security Classification Authority 



2b Declassification Downgrading Schedule 



3 Distribution/Availability of Report 

Approved for public release; distribution is unlimited. 



4 Performing Organization Report Number(s) 



5 Monitoring Organization Report Number(s) 



6a Name of Performing Organization 

Naval Postgraduate School 



6b Office Symbol 
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7a Name of Monitoring Organization 

Naval Postgraduate School 



6c Address (city, state, and ZIP code) 

Monterey, CA 93943-5000 



7b Address (city, state, and ZIP code) 

Monterey, CA 93943-5000 



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li Tide (include security classification) METEOROLOGICAL FEATURES DURING PHASE I OF THE COORDINATED 
EASTERN ARCTIC EXPERIMENT (CEAREX) FROM 17 SEPTEMBER 1988 TO 7 JANUARY 1989 



12 Personal Author(s) Stephanie W. Hamilton 



13a Type of Report 

Master's Thesis 



13b Time Covered 
From To 



14 Date of Report (year, month, day) 
March 1991 



15 Page Count 

98 



16 Supplementary Notation The views expressed in this thesis are those of the author and do not reflect the official policy or po- 
sition of the Department of Defense or the U.S. Government. 



17 Cosati Codes 



Field 



Group 



Subgroup 



18 Subject Terms (continue on reverse if necessary and identify by block number) 

arctic meteorology', arctic storms, arctic climate, arctic research, boundary layer front, 

marginal ice zone, CEAREX 



19 Abstract (continue on reverse if necessary and identify by block number) 

The synoptic and mesoscale meteorological conditions were analyzed for Phase I of the Coordinated Eastern Arctic Ex- 
periment (CEAREX) from 17 September 1988 to 7 January 1989. Meteorological observations from a research ship (R/V 
Polarbjoern), an array of drifting buoys and satellite imagery from DMSP and NOAA satellites were the primary tools for 
analysis. Several short periods of high cyclone activity followed by long periods of high pressure dominated the weather 
pattern in the eastern Arctic Ocean from Greenland to Novaya Zemlya for this period. Two case studies are presented. An 
infrequent cyclogenesis event that formed within a strong baroclinic zone over Arctic pack ice was observed in a "baroclinic 
leaf' on satellite imagery. Ship and drifting buoy observations provided critical insight to the location and intensity of the 
'leaf's" subsequent vertical development to the surface. In the second study, a boundary layer front was observed in the East 
Greenland Sea by satellite imagery. The front then moved northeast into Fram Strait and a polar low formed at the northern 
end of the front. The event lasted less than 24 h and would not have been observed except through satellite imagery. 



20 Distribution 'Availability of Abstract 

H unclassified 'unlimited Q same as report D DTIC users 



21 Abstract Security Classification 
Unclassified 



22a Name of Responsible Individual 

Kenneth L. Davidson 



22b Telephone (include Area code) 

(408) 646-2563 



22c Office Symbol 

MR(Ds) 



DD FORM 1473,84 MAR 



83 APR edition may be used until exhausted 
All other editions are obsolete 



security classification of this page 

Unclassified 



Approved for public release; distribution is unlimited. 

Meteorological Features during Phase I of the 

Coordinated Eastern Arctic Experiment (CEAREX) 

from 17 September 1988 to 7 January 1989 



by 



Stephanie W. Hamilton 

Lieutenant, United States Navy 

B.S., Old Dominion University, 1980 

Submitted in partial fulfillment of the 
requirements for the degree of 

MASTER OF SCIENCE IN METEOROLOGY AND PHYSICAL 

OCEANOGRAPHY 

from the 

NAVAL POSTGRADUATE SCHOOL 
March 1991 



Robert L. Haney, Chairrnlin, 
Department of Meteorology 



ABSTRACT 

The synoptic and mesoscale meteorological conditions were analyzed for Phase I of 
the Coordinated Eastern Arctic Experiment (CEAREX) from 17 September 1988 to 7 
January 1989. Meteorological observations from a research ship (R/V Polarbjoern), an 
array of drifting buoys and satellite imagery from DMSP and NOAA satellites were the 
primary tools for analysis. Several short periods of high cyclone activity followed by 
long periods of high pressure dominated the weather pattern in the eastern Arctic Ocean 
from Greenland to Novaya Zemlya for this period. Two case studies are presented. An 
infrequent cyclogenesis event that formed within a strong baroclinic zone over Arctic 
pack ice was observed in a "baroclinic leaf on satellite imagery. Ship and drifting buoy 
observations provided critical insight to the location and intensity of the "leafs" subse- 
quent vertical development to the surface. In the second study, a boundary layer front 
was observed in the East Greenland Sea by satellite imagery. The front then moved 
northeast into Fram Strait and a polar low formed at the northern end of the front. The 
event lasted less than 24 h and would not have been observed except through satellite 
imagery. 



in 



CI 



TABLE OF CONTENTS 

I. INTRODUCTION 1 

II. BACKGROUND 4 

A. FACTORS IN ARCTIC CLIMATOLOGY 4 

1. Amount of Daylight and Solar Elevation 4 

2. Circumpolar Vortex 4 

3. Marginal Ice Zone 5 

4. Temperature Inversion 5 

5. Arctic Ocean Surface Circulation 7 

B. FALL AND EARLY WINTER SYNOPTIC CLIMATOLOGY 8 

1 . Surface Air Temperature Patterns 8 

2. Surface Pressure Patterns 10 

3. 700 mb Pattern 11 

4. Cyclone Tracks 12 

C. SIGNIFICANT ATMOSPHERIC FEATURES 17 

1. Baroclinic Leaf 17 

2. Polar Lows 19 

3. Boundary Layer Fronts 21 

4. Cloud Features in Satellite Imagery 22 

a. Surface Streamlines 22 

b. Arctic Fronts 23 

c. Polar Lows 23 

III. SYNOPTIC OVERVIEW OF PHASE I 24 

A. DATA SOURCES 24 

1. R/V Polarbjoern 24 

2. Surface Buoys 24 

3. Surface and Upper Air Reports and Global Analyses 26 

4. Meteorological Satellite Imagery 29 

B. GENERAL SYNOPTIC FEATURES 30 

1. September 1988 30 



IV 



2. October 1988 33 

3. November 1988 38 

4. December 1988 to 7 January 1989 42 

5. Summary 46 

C. TEMPERATURE INVERSIONS 50 

IV. CASE STUDIES 53 

A. CYCLOGENESIS EVENT OVER R/V POLARBJOERN (12 OCTOBER 
1988) 53 

1. Cyclogenesis Event 53 

2. Summary and Conclusions 70 

B. BOUNDARY LAYER FRONT AND POLAR LOW DEVELOPMENT . . 71 

1. Overview 71 

2. Satellite Imagery and Streamline Analysis 71 

3. Comparison with Other Studies 79 

V. SUMMARY AND RECOMMENDATIONS 80 

A. SUMMARY 80 

B. RECOMMENDATIONS 81 

LIST OF REFERENCES 82 

INITIAL DISTRIBUTION LIST 86 



LIST OF TABLES 

Table 1. REPORTING STATIONS, LOCATION, AND DATA REPORTS ... 27 

Table 2. INVERSION TYPE AND FREQUENCY DURING PHASE I 50 

Table 3. FREQUENCY OF INVERSIONS SUMMARIZED FROM 

VOWINCKEL AND ORVIG DATA 50 



VI 



LIST OF FIGURES 

Fig. 1. Key geographic locations of the circumpolar Arctic (from Zumberge 1986) 3 

Fig. 2. Average Ice conditions in the Arctic (from Tchernia 1980) 6 

Fig. 3. Frequency of arctic inversion types during the year (from Vowinckel and 

Orvig 1970) 7 

Fig. 4. Ocean circulation of the Arctic (from Tchernia 1980) 8 

Fig. 5. Mean Surface Air Temperatures (°C) for a) October and b) January (from 

Sater et al. 1971) 9 

Fig. 6. Mean Sea Level Pressure (mb) for a) October and b) January (from Sechrist 

et al. 1989) 10 

Fig. 7. Autumn a) cyclone and b) anticyclone percent frequencies (from Serreze and 

Barry 1988) 11 

Fig. 8. 700 mb mean height (m) for a) October and b) January (from Sechrist et al. 

1989) 12 

Fig. 9. a) Winter and b) summer cyclone tracks (from Serreze and Barry 1988) . . 13 
Fig. 10. Cyclone Tracks for a) October, b) December, c) January and d) February 

(from Gorshkov 1983) 14 

Fig. 11. Autumn synoptic patterns (from Gorshkov 1983) 16 

Fig. 12. Baroclinic Leaf Cloud Patterns (from Weldon 1986b) 18 

Fig. 13. a) 500 mb and b) Surface Analysis with a Baroclinic Leaf (from Weldon 

1986b) 19 

Fig. 14. Baroclinic Leaf Embedded in Upper Level Trough (from Weldon 1979) . . 19 
Fig. 15. Vertical cross-section of a boundary layer front (from Shapiro and Fedor 

1989) 22 

Fig. 16. Buoy array and R/V Polarbjoern positions during drift phase for dates 

September 20 to January 7 25 

Fig. 17. Synoptic map of eastern Arctic Circle showing reporting stations 28 

Fig. 18. a) Mean and b) anomaly sea level pressure for September 1988 31 

Fig. 19. a) Mean and b) anomaly 500 mb geopotential heights for September 1988 31 
Fig. 20. a) Mean and b) anomaly 1000-500 mb thickness for September 1988 .... 32 

Fig. 21. R/V Polarbjoern time series for September 33 

Fig. 22. a) Mean and b) anomaly sea level pressure for October 1988 34 



vu 



Fig. 23. a) Mean and b) anomaly 500 mb geopotential heights for October 1988 . . 35 

Fig. 24. a) Mean and b) anomaly 1000-500 mb thickness for October 1988 35 

Fig. 25. R/V Polarbjoern time series for October 38 

Fig. 26. a) Mean and b) anomaly sea level pressure for November 1988 39 

Fig. 27. a) Mean and b) anomaly 500 mb geopotential heights for November 1988 39 
Fig. 28. a) Mean and b) anomaly 1000-500 mb thickness for November 1988 .... 40 

Fig. 29. NOAA-11 Satellite imagery on 140810Z November 1988 41 

Fig. 30. R/V Polarbjoern time series for November 42 

Fig. 31. a) Mean and b) anomaly sea level pressure for December 1988 43 

Fig. 32. a) Mean and b) anomaly 500 mb geopotential heights for December 1988 43 
Fig. 33. a) Mean and b) anomaly 1000-500 mb thickness for December 1988 .... 44 

Fig. 34. R/V Polarbjoern time series from 1 December to 10 January 46 

Fig. 35. Cyclones Tracks for Phase I of CEAREX 48 

Fig. 36. Examples of Inversion Types during CEAREX 51 

Fig. 37. DMSP satellite mosaic for 1 12320 UTC October 1988 54 

Fig. 38. NOGAPS 500 mb analysis for 120000 UTC October 1988 55 

Fig. 39. DMSP satellite mosaic at 120828 UTC October 1988 56 

Fig. 40. NOAA-10 satellite image for 121012 UTC October 1988 57 

Fig. 41. NOGAPS 500 mb analysis for 121200 UTC October 1988 58 

Fig. 42. R/V Polarbjoern and buoy positions for October 1988 59 

Fig. 43. Pressure and temperature time series for drifting buoys 60 

Fig. 44. Surface analysis for 121200 UTC October 1988 61 

Fig. 45. Time series of observations for R/V Polarbjoern (10-17 October) 62 

Fig. 46. Surface analysis for 121800 UTC October 1988 62 

Fig. 47. NOGAPS 500 mb analysis at 130000 UTC October 1988 63 

Fig. 48. Surface analysis at 130000 UTC October 1988 64 

Fig. 49. Surface analysis for 131800 UTC October 1988 65 

Fig. 50. NOAA-10 satellite image at 130950 UTC October 1988 66 

Fig. 51. NOGAPS 500 mb analysis for 131200 UTC October 1988 67 

Fig. 52. DMSP satellite mosaic at 132240 UTC October 1988 68 

Fig. 53. DMSP satellite mosaic at 140749 UTC October 1988 69 

Fig. 54. NOAA 10 Satellite Image at 100915 UTC October 1988 73 

Fig. 55. NOAA 10 satellite image at 101056 UTC October 1988 75 

Fig. 56. NOAA 10 satellite image at 101307 UTC October 1988 76 

Fig. 57. DMSP satellite image at 102318 UTC October 1988 78 



Vlll 



ACKNOWLEDGMENTS 

This thesis could not have been accomplished without the assistance of a great 
number of people. I would like to thank my advisors, Dr. Kenneth L. Davidson and 
Dr. Carlyle H. Wash for their support, direction, and guidance every step of the way. I 
would especially like to extend my gratitude to Mr. Robert Fett of the Naval 
Oceanographic and Atmospheric Research Laboratory for his inspiration and assistance 
in interpreting my data and putting together this thesis. I would also like to thank Mr. 
Tom Lee of NOARL and Mr. Dennis Laws of FNOC for their assistance. 

My deepest appreciation, goes to my husband David and my daughters Samantha 
and Jennifer. Their love, encouragement, and support saw me through the tough times. 



IX 



I. INTRODUCTION 

The Arctic Ocean is arguably one of the most difficult areas in the world to make 
an accurate meteorological forecast. This is due to the limited observational data, which 
is critical to making good analyses. Without a complete understanding of the present 
state of the atmosphere, it is impossible to consistently produce accurate forecasts. This 
thesis will provide additional analyses during a meteorological experiment of Arctic 
weather to gain insight into the unique forecasting problems of the Arctic. The use of 
satellite imagery will be used extensively in this thesis to enhance the analysis. 

United States interest in Arctic research has increased significantly in the past dec- 
ade. The Arctic Research and Policy Act of 1984 established policy and goals for sci- 
entific research in the Arctic. On 28 June 1985, Executive Order 12501 was signed 
establishing an Arctic Research Committee (National Science Foundation 1987). Fol- 
lowing the Arctic Research Plan in 1987, the United States, and the Navy in particular, 
have participated in several multinational Arctic experiments. The Marginal Ice Zone 
Experiments (MIZEX-83, MIZEX-84, and MIZEX-87) were studies of the physical 
processes of the ocean, ice, and the atmosphere. The Coordinated Eastern Arctic Ex- 
periment (CEAREX), from September 1988 through May 1989, was a continuation of 
studies in this area with further U.S. Navy involvement. 

The Navy's primary meteorological interest is to learn of the effect of Arctic weather 
on naval operations and particular areas of study include polar fronts and deep con- 
vection. Specific regions of interest for the Navy are the marginal ice zone (MIZ), Fram 
Strait, Greenland and Norwegian Seas, and the central Arctic basin (National Science 
Foundation 1988). 

This thesis will examine meteorological and oceanographic features in the lower at- 
mosphere during Phase I of CEAREX from 17 September 1988 through 7 January 1989. 
In Phase I, the U.S. Coast Guard ice breaker, Northwind, led the R/V Polarbjoern into 
multiyear pack ice north of Svalbard, Norway. During CEAREX, the R/V Polarbjoern 
was used to gather meteorological information. In addition to the ship's surface and 
upper air reports, six buoys were deployed and collected surface observations of pressure 
and temperature. From 17 September to 15 November, the R/V Polarbjoern was 
moored to a large ice floe and drifted slowly southward with the advancing ice pack 
under the influence of northerly winds. The ice floe was destroyed on 15 November by 



a strong northwesterly wind event. The Rj V Polarbjoern continued to drift slowly south 
while trapped in the Arctic ice pack. A strong storm with high winds in early January 
allowed the ship to break free on 7 January. 

The major geographic and oceanographic points of interest for this study appear on 
Fig. 1. The ship was located northeast of Svalbard. Spitzbergen is the largest island to 
the west. The two smaller islands east of Spitzbergen are Northeast Land and Edge Is- 
land, located northeast and southeast, respectively, of Spitzbergen. The RjV Polarbjoern 
passed very close to Kvitoya, the small island located due east of Northeast Land. A 
branch of the Norway Current runs north along the west coast of Spitzbergen heading 
into the Arctic basin and is referred to as Fram Strait. The MIZ is located in Fram 
Strait and East Greenland Sea throughout the year. 

This thesis presents a climatological summary along with significant meteorological 
features indigenous to the region in Chapter II. Chapter III details data sources and 
then presents an overview of the synoptic situation during Phase I for the region. Two 
case studies are presented in Chapter IV. One case study involves an infrequent 
cyclogenesis event that occurred over the RjV Polarbjoern on 12 October 1988, located 
in Arctic pack ice at the time. The second case study pertains to the formation of a 
boundary layer front in Fram Strait on 10 October 1988 that evolved into a polar low. 
Summary and recommendations follow in Chapter V. 



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Fig. 1. Key geographic locations of the circumpolar Arctic (from Zumberge 1986) 



II. BACKGROUND 

There are significant climatological aspects that dominate Arctic weather: sunlight, 
circumpolar vortex, ice cover and temperature inversion. Each can cause great vari- 
ability in Arctic weather, from month to month and from year to year. The Arctic ocean 
circulation also plays an important role in the formation of sea ice and temperature 
gradients. The climatological synoptic patterns for fall and early winter are presented 
for air temperatures, sea level pressure, 700 mb, and cyclone tracks. Significant atmo- 
spheric features seen in the Arctic are defined and their satellite characteristics presented. 

A. FACTORS IN ARCTIC CLIMATOLOGY 

1. Amount of Daylight and Solar Elevation 

Sunlight is one of two prime heat sources for the Arctic. Decreases in the 
amount of sunlight combined with the low solar elevation at high latitudes cause ex- 
tended periods of radiational heat loss from the surface. Late September and early Oc- 
tober represent the strongest transition period as Arctic daylight each day is 25 minutes 
less. The amount of sunlight changes from approximately 14 hours of sunlight on 17 
September to continuous darkness by approximately 10 October at 80°N. Even with 
daylight present in late September and early October, the sun has a very low elevation. 
For example, on 1 October the solar elevation is only 6° 50' above the horizon. North 
of 80°N. there is complete darkness during Phase I and as a result the visible channels 
in satellite imagery will have considerable variation in illumination in the areas on the 
border between daylight, twilight, and darkness. 

2. Circumpolar Vortex 

The most significant factor in the large scale surface weather patterns is the 
position of the cold-core circumpolar vortex. The polar vortex is the mid and upper level 
atmospheric large scale cyclonic circulation centered at the pole. The position and 
strength of the vortex depends on the degree of the north-south temperature gradient. 
The vortex is strongest and penetrates further south during the winter months when the 
differential heating is the greatest. October is a transitional month when the vortex is 
moving from its maximum northern extent during the summer to its maximum southern 
extent during the winter. The band of upper level westerlies on the periphery of the 
vortex steer the surface cyclones into the Arctic. As the planetary wave number in- 
creases, the more upper level troughs and ridges are present, which increase the number 



of surface cyclones in the Arctic. This provides much variability in the Arctic climate 
as warm air advection from cyclones moving into the central Arctic basin is the second 
prime heat source for the Arctic (Vowinckel and Orvig 1970). 

3. Marginal Ice Zone 

The presence of ice is also a major controlling factor in Arctic weather. Average 
ice conditions are illustrated in Fig. 2. The Naval Polar Oceanography Center (NPOC) 
prepares operational weekly ice edge analyses which were used in this study. The extent 
of sea ice is at a minimum in September and October. The ice edge penetrates farther 
south in late fall and winter, with a maximum extent from March to April (Stringer et 
al. 1984). The difference between the minimum and maximum extent of sea ice is greater 
east of Svalbard than west of Svalbard due to the presence of a warm ocean current (a 
branch of the Norway Current) penetrating northward along the west coast of 
Spitzbergen throughout the year. The ocean currents play a large role in the extent of 
sea ice and will be discussed in a subsequent section. As noted in Fig. 2, there is almost 
always a permanent ice sheet affixed to the east coast of Greenland and the MIZ region 
is always present in Fram Strait and Greenland Sea. There are sharp temperature and 
moisture gradients in the vicinity of the MIZ. Also the open water in Fram Strait 
produces considerable convective cloudiness. Low clouds and fog are the dominant 
weather features in this region. 

4. Temperature Inversion 

The fourth aspect of Arctic climate is the temperature inversion that is almost 
always present in the Arctic as shown in Fig. 3. Long periods of darkness result in the 
presence of a semi-permanent surface temperature inversion over the ice as a function 
of radiational cooling. When light surface winds preclude mixing from above and skies 
are clear, maximum surface temperature inversions occur (Sechrist et al. 1989). Inv- 
ersions also exist due to subsidence, advection, and mixing. Surface inversions on the 
average extend up to 2 km and have a temperature increase of 5°C (Shultz 1987). These 
low-level inversions preclude mixing from above, trap fog and suppress convection. A 
very cold, relatively moist, and stable surface layer exists over the Arctic ice cap with a 
relatively warm, dry layer above for the majority of the fall and winter. 



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Fig. 3. Frequency of arctic inversion types during the year (from Vowinckel and 
Orvig 1970) 



Elevated inversions occur as frequently as surface inversions during October as 
seen in Fig. 3. By early winter, surface inversions dominate the central Arctic basin. 
Elevated inversions can result from warm air advection aloft or by subsidence (sharp 
decrease of relative humidity with height). These inversions are less intense than surface 
inversions with a thickness of .5 to .9 km and temperature increase of only 1.2°C 
(Vowinckel and Orvig 1970). 

5. Arctic Ocean Surface Circulation 

The general circulation of the Arctic Ocean is depicted in Fig. 4. A branch of 
the North Atlantic Drift, the Norway Current brings warm and salty water into the 
Arctic circle north along the west coast of Spitzbergen in Fram Strait as far as 80°N. 
This warm tongue of water is reflected in the Arctic ice pack formation and in the mean 
surface air temperature to be discussed in the following section. The East Greenland 
Current runs south along the east coast of Greenland bringing cold and fresh water from 
the central Arctic basin to the tip of Greenland. This intrusion of cold water maintains 
a permanent ice sheet attached to the east coast of Greenland. The northbound Norway 
Current and the southbound East Greenland Current set up a cyclonic eddy in the 
Greenland and Norwegian Seas as illustrated in Fig. 4. 




Fig. 4. Ocean circulation of the Arctic (from Tchernia 1980) 



B. FALL AND EARLY WINTER SYNOPTIC CLIMATOLOGY 

There are many important factors to consider when examining meteorological fea- 
tures in the Arctic as presented above. Fall and early winter are a time of great transi- 
tion in the Arctic in the amount daylight, the temperature gradient, the strength of the 
circumpolar vortex, and extent of sea ice. A thorough knowledge of the climate and 
features indigenous to the Arctic is a crucial factor in the correct analysis of synoptic 
conditions. 

1. Surface Air Temperature Patterns 

Temperature changes in the Arctic are small and steady as the temperature of 
the ice regulates the surface air temperature. Although the amount of sunlight decreases 
rapidly over the most northern latitudes, the temperature of the ice slowly cools until it 
reaches its wintertime minimum in February. The central Arctic basin has an average 



air temperature of 0°C during the summer and slowly cools to an average of -18°C in 
October and -34°C in January. The Greenland Sea, Fram Strait, and Svalbard region 
have a weak horizontal temperature contrast of 2-5°C during the summer season which 
increases to 12-14°C in October. The maximum temperature gradient occurs in the 
winter which increases to a contrast of 18-20°C from the southern portion of Fram Strait 
to north of Svalbard. The tight temperature gradients in this region are illustrated in 
Fig. 5 for October and January. 




Fig. 5. Mean Surface Air Temperatures (°C) for a) October and b) January (from 
Sateret al. 1971) 



Over the Arctic ice pack warm air advection, usually from North Atlantic 
cyclones, can increase surface air temperatures. Soon after these events, the surface air 
rapidly cools to its normal values. The surface air temperature in the MIZ is greatly 
influenced by the presence of ice or the relatively warm ice-free waters. The effect of the 
warm Norway Current is readily apparent in the temperature gradient in the MIZ. 

Surface air temperature anomalies are persistent in the fall when variations in 
the ice coverage are the greatest. Temperatures will also vary due to the intrusion of 
North Atlantic cyclones which can increase surface temperatures by as much as 25°C. 
Walsh and Chapman (1990) have observed that the North Atlantic MIZ has shown 
significant warming events over the last twenty years. 



2. Surface Pressure Patterns 

The monthly mean sea level pressure pattern for October and January are pre- 
sented by Sechrist et al. (1989) in Fig. 6. The pressure charts were compiled by the 
Applied Physics Laboratory at the University of Washington. Data obtained from a 
drifting buoy network in the Arctic from 1979-1985 was used to construct the charts. 
High pressure and anticyclonic flow dominate the Arctic basin from September through 
January with a maximum in winter. A high pressure center over Greenland during the 
summer moves toward the western Arctic during the winter months. A low pressure 
trough persists from a low pressure center over Iceland northeast through the 
Norwegian Sea to Novaya Zemlya. In October, the Icelandic low intensifies and reaches 
a maximum during the winter months. Monthly sea level pressure anomalies are most 
persistent during the fall east of Greenland. The large variability in this region is asso- 
ciated with the intrusion of North Atlantic cyclones (Walsh and Chapman 1990). 



OCTOBER 



JANUARY 




Fig. 6. Mean Sea Level Pressure (mb) for a) October and b) January (from Sechrist 
et al. 1989) 

Serreze and Barry (1988) used data from a network of drifting buoys to analyze 
surface pressure patterns in the Arctic. Autumn (September to November) percent fre- 
quencies for cyclones and anticyclones are summarized in Fig. 7. Serreze and Barry 
(1988) counted as cyclones those systems that appeared on at least two consecutive 
charts, had one closed isobar at 4 mb contour intervals, and reached a minimum pressure 



10 



ofless than 1012 mb. Anticyclones must have a maximum pressure equal or greater to 
1012 mb. There is a cyclone frequency maximum near Svalbard in all seasons except 
summer where the maximum frequency of cyclones shifts to the central Arctic basin. 
Autumn is a transition period where the cyclone frequency maximum is shifting from the 
central Arctic basin to its winter maximum between Svalbard and Novaya Zemlya. 
Anticyclone frequencies remain the highest in the western Arctic basin in all seasons 
with the highest frequencies in the spring and fall. Greenland was omitted in Serreze and 
Barry (1988) frequency studies because of the problem of reducing the pressures over the 
Greenland ice cap to sea level. 




Fig. 7. Autumn a) cyclone and b) anticyclone percent frequencies (from Serreze and 
Barry 1988) 

3. 700 mb Pattern 

The circumpolar vortex can be located using the 700 mb chart. The mean 700 
mb heights for October and January presented by Sechrist et al (1989) are depicted in 
Fig. 8. The band of westerlies around the vortex lies far to the south of the Arctic circle 
from October through January. There is a deep trough that extends from Greenland 
south in the North Atlantic in September and October and cyclones tracking into the 
Arctic from the North Atlantic are steered northeast toward Svalbard. The circumpolar 
vortex strengthens from October to January as the north to south temperature gradient 
is maximized and two low height centers establish over the Arctic basin. The southward 



11 



extent of the circumpolar vortex will dominate the weather near Svalbard in any season. 
A strong vortex extending south of Svalbard will decrease cyclonic activity in the region. 
Lows that move northward under the vortex will become occluded and stagnate over the 
Central Arctic basin. 




Fig. 8. 700 mb mean height (m) for a) October and b) January (from Sechrist et 
al. 1989) 

4. Cyclone Tracks 

Serreze and Barry (1988) compiled cyclone tracks from 70 to 90 °N for the 
1979-85 period. The prevalent cyclone tracks for winter and summer are illustrated in 
Fig. 9. During the winter three to five cyclones per season entered the Arctic basin from 
the North Atlantic, which is the most frequent entrance zone. There is a high variability 
from year to year and in some years the North Atlantic track did not dominate. Serreze 
and Barry (1988) also found that upper level troughs and lows tracked from Baffin Bay 
east across Greenland into the Greenland Sea to Svalbard. Summer cyclones from the 
North Atlantic track north over Svalbard at the rate of 2 to 4 per season but they seldom 
enter the western Arctic basin. 



12 




Fig. 9. a) Winter and b) summer cyclone tracks (from Serreze and Barry 
1988): the width of the arrow indicates the importance of the track. 

The comprehensive Atlas of the Arctic Ocean by Gorshkov (1983) depicts the 
trajectories and frequencies of cyclones and anticyclones in the Arctic for every month. 
The information was compiled from global synoptic weather charts from 1960 to 1970. 
Only rapidly moving cyclones and anticyclones were included. The tracks were calcu- 
lated by averaging the actual path in one direction in groups of 400-500 km wide zones. 
The frequency of all cyclones and anticyclones (slow and fast moving) were calculated 
as a percentage of the number of days in a month. The average climatic cyclone tracks 
for October, December, January and February as compiled by Gorshkov (1983) are 
presented in Fig. 10. The widest arrows represent a frequency of 4 to 6 days of the 
month, the hollow arrows 2 to 4 days per month, and the thin solid arrows represent a 
frequency of less than 2 days per month. 

The charts for October and December show the major cyclone track from 
Iceland northeast through the Norwegian Sea south of Svalbard, then northeast over 
Franz Joseph Land or southeast to Novaya Zemlya. The cyclone frequency for October 
is higher than November through January. 



13 




Fig. 10. Cyclone Tracks for a) October, b) December, c) January and d) February 
(from Gorshkov 1983) 

The charts for January and February in Fig. 10 show very different tracks from 
the previous three months. January has the major cyclone track east northeast from 
Iceland to north of Norway then east along 72°N. A secondary track from north of 
Greenland has cyclones moving southeast to Svalbard then a major track resumes 
southeast from Svalbard to northwest U.S.S.R. A secondary track also exists from 
Norwegian Sea northeast between Svalbard and Franz Joseph Land. February is in- 
cluded because it is the only month that indicates a major region of cyclogenesis inside 
the Arctic circle. The maximum frequency of cyclones and the change in the storm paths 
from minor to major tracks suggest a major area of cyclogenesis between Svalbard and 
Norway. Lows from northern Greenland track southeast to Svalbard and then to 
Novaya Zemlya. The major cyclone tracks are from the region of cyclogenesis south and 
southeast to northern Europe. These tracks differ sharply from the results compiled by 



14 



Scrreze and Barry' (1988). The major cyclone tracks for their study have all cyclones 
heading into the central Arctic basin for both winter and summer seasons. Gorshkov 
(1983) presents much more variability in Arctic cyclone tracks than Serreze and Barry 
(1988). Gorshkov illustrates many different trajectories between 70 and 90 °N. Serreze 
and Barry's major cyclone tracks extend south to north into the central Arctic basin. 
Gorshkov depicts a major cyclone track that extends from Iceland northeast through 
Barents Sea to Novaya Zemlya. He also has trajectories extending from north of 
Greenland southeast through the Barents Sea. Serreze and Barry indicate a winter 
cyclone rate of three to five per season while Gorshkov lists up to four to six in October 
alone through the major track. The cyclone frequency is significantly higher in 
Gorshkov's study. 

Gorshkov (1983) presents sixteen types of synoptic patterns (called processes in 
the translation) covering two seasons and lists the frequencies for each type for every 
month. Gorshkov used the diurnal weather maps for Eurasia and the Northern Hemi- 
sphere from 1939-1962 for June to November data, and 1948-1968 maps for compiling 
the December through May data. All the synoptic type patterns were formed into the 
groups on the basis of the overall distribution of pressure fields over the Arctic Ocean. 
The letter 'H' denotes a cyclone and 'B' denotes an anticyclone. The heavy arrows are 
cyclone tracks and the light arrows are anticyclone tracks. 

Six synoptic patterns that cover summer, fall, and winter constructed by 
Gorshkov (1983) are illustrated in Fig. 11. Autumn-winter climate patterns that have a 
30 to 40 percent occurrence in each month from October to January are depicted in 
Fig. 1 la-c. In Fig. 1 la, a cyclone lies over the Barents Sea between Svalbard and Franz 
Joseph Land. A depression over the Barents Sea and a principle cyclone track from 
Norwegian Sea east to Novaya Zemlya is shown in Fig. lib. Multiple low pressure 
centers over Norwegian Sea and northwest of Svalbard are reflected in Fig. lie. 

A summer-autumn situation (Fig. lid) shows a low over Barents Sea and a 
principle track southeast to Novaya Zemlya. A summer-autumn process with a low in 
the Norwegian Sea and a principle cyclone track northwest over Svalbard is depicted in 
Fig. lie. Fig. 1 If reflects an autumn- winter scenario with an anticyclone over the 
Arctic basin and a depression over the southern Barents Sea. The principle cyclone track 
is east through the Norwegian Sea and southern Barents Sea. Fig. lid through f have 
a 20% frequency in each month from September through December. 

The tracks of the North Atlantic cyclones steered by the position of the 
circumpolar vortex has its greatest effect on the climate of the MIZ in the Greenland 



15 




Fig. 11. Autumn synoptic patterns (from Gorshkov 1983) 

and Norwegian Seas, Fram Strait, and vicinity of Svalbard. Low pressure systems can 
regenerate in the MIZ as well as off the east coast of Greenland and the vicinity of 



16 



Novaya Zemlya. However, North Atlantic cyclones typically stagnate and fill near 
Novaya Zemlya. The surface low pressure systems tracking from the North Atlantic 
onto the polar ice cap rise up over the cold layer of Arctic air and become occluded. 
Once the cyclones move over the ice basin their tracks are slow, erratic, and difficult to 
predict. 

C. SIGNIFICANT ATMOSPHERIC FEATURES 

There are many significant features which are common and unique to the Arctic. 
The first section covers the "baroclinic leaf which can be seen in satellite imagery' during 
Phase I. The second section covers the importance of polar lows which are very com- 
mon in the Norwegian and Barents seas. Boundary layer fronts which form in Fram 
Strait are described in the third section. Several features visible on the Arctic satellite 
imagery used in this thesis will be discussed in the final section. 

1. Baroclinic Leaf 

Weldon (1979) defines a "baroclinic leaf as the elongated cloud pattern that 
forms prior to the comma shaped cloud pattern. The "leaf is associated with 
frontogenesis aloft and usually forms in a westerly wind field. The "baroclinic leaf cloud 
pattern delineates a boundary that is being deformed and is a precursor to comma 
shaped systems. Weldon (1986) states that 75% of the "baroclinic leaf systems form 
comma systems with surface cyclogenesis. In the deformation boundary a new 
baroclinic zone forms downstream from an established baroclinic area. New clouds are 
forming and precipitation becomes more organized but surface pressures have not low- 
ered and there is no closed surface circulation. There is frequently a surface trough or 
cyclonic shear zone present. The system usually develops vertically and surface defor- 
mation also occurs. Typical shapes for "baroclinic leafs" are illustrated in Fig. 12 from 
Weldon (1986b). 



17 




Fig. 12. Baroclinic Leaf Cloud Patterns (from Weldon 1986b) 

Upstream of the deformation zone, in the pre-existing baroclinic zone, the upper 
level winds are increasing and the flow is confluent. Downstream, the wind speeds are 
decreasing and the flow is diiluent. There is cyclonic flow north of the zone and 
anticyclonic flow south of the deformation area. Fig. 13a shows a "baroclinic leaf 
embedded in the upper level flow. Fig. 13b reflects the surface pressure pattern under 
a "baroclinic leaf system. The maximum winds at the upper level are upstream from the 
"leaf and downstream speeds are lower. The jet stream maximums are south of the 
sharp northern boundary of the "leaf. This is unlike a cirrus shield where the jet axis 
lies on the northern edge of the cloud pattern. Significant precipitation will occur on the 
western or trailing edge of the "leaf. At the surface, under the southern boundary of 
the "leaf, a surface frontal zone will typically lie parallel to the cloud pattern. 



18 




Fig. 13. a) 500 mb and b) Surface Analysis with a Baroclinic Leaf (from Weldon 
1986b) 

The "baroclinic leaf cloud system will not usually move in the direction of the 
flow, but will rotate slightly counterclockwise. The "leaf can form on the forward side 
of an upper level trough. Weldon (1986a) describes formation of a "baroclinic leaf 
cloud pattern in a high amplitude upper level trough. Fig. 14 shows a "leaf forming 
on the downstream side of a high amplitude upper level trough. High cloudiness is 
present on the warm side of the jet axis. 




Fig. 14. Baroclinic Leaf Embedded in Upper Level Trough (from Weldon 1979) 

2. Polar Lows 

Businger and Reed (1989) define a polar low as a "small synoptic- or 
subsynoptic-scale cyclone that forms in a cold air mass poleward of major jet streams 
or frontal zones and whose main cloud mass is largely of convective origin." As cold 



19 



arctic air flows off the Arctic ice basin or the Greenland ice cap it turns strongly 
cyclonically over the open ocean wrapping itself around the relatively warmer air over 
the ice-free water. Hence, polar lows are thought to be warm core and are sometimes 
compared to tropical cyclones because some form the distinctive clear eye (Rasmussen 
1989). Polar lows have weak vertical tilt, experience their strongest circulation at the 
surface, exhibit low-level cyclonic shear, and the geostrophic wind backs with height. 
Polar lows form over open oceans and can be seen on satellite imagery as comma or 
spiral shaped cloud patterns. They range in size from 50 to 1000 km in diameter and can 
produce strong winds and heavy precipitation. In the seas north and west of Norway, 
polar lows form most frequently from October through April with a maximum occur- 
rence in January (Businger and Reed 1989). 

Of the three types of polar lows defined by Businger and Reed (1989), the 
Arctic-front type is the most common in the Greenland, Norwegian, and Barents Seas. 
Arctic-front type polar lows form in the cold air mass behind arctic fronts. Arctic fronts 
are difficult to detect on weather maps because tight temperature gradients may not be 
evident. However, Arctic fronts can be seen on satellite imagery as described in Section 
1, above. Arctic fronts can be located along the MIZ where relatively warm water meets 
the polar ice pack. Differential heating of the boundary layer over the warm water and 
the ice cover causes a strong low-level baroclinic zone. Polar lows form when the cold 
air from the polar ice pack or Greenland continent flows over the open waters of the 
Greenland, Norwegian, or Barents Seas. Clouds streets as described in Section 1. indi- 
cate the flow of air off the ice pack over the open water. 

Arctic-front type polar lows can form in reversed shear situations where the 
storm motion is in the opposite direction of the thermal wind. In this case, the cloud 
pattern lies upstream of the trough. Reverse shear polar lows have been observed north 
and west of Norway (Businger and Reed 1989) and in the warm intrusion of water west 
of Spitzbergen. 

Modeling polar lows and especially Arctic-front polar lows has proven to be an 
almost impossible task due to their small size. The Arctic-front type polar low is difficult 
to forecast because of the scarce observations in the regions of formation. The most 
important tool for detecting and analyzing polar lows are infrared images. The Polar 
Lows Project (Lystad 1986) identified three criteria for polar low formation: (1) cold air 
advection at the sea surface; (2) 850-500 mb thickness layer must be less than 3960 m 
(adjust with sea surface temperature); and (3) 500 and 700 mb levels must have cyclonic 
or zero curvature. 



20 



3. Boundary Layer Fronts 

Boundary layer fronts in the Arctic are associated with outbreaks of cold Arctic 
air and appear as bands of enhanced cumulus activity formed from diabatically forced 
vertical circulations. Boundary layer fronts typically form when the surface wind flow 
is parallel to snow or ice covered surfaces and ice free water areas. Ice edge boundary 
layer fronts can maintain their identities for long distances while being advected by the 
synoptic flow. 

Shapiro and Fedor (1989) studied the case of a stationary boundary layer front 
that formed on 14 February 1984 from low-level northerly flow from an east-west ori- 
ented ice edge west of Spitzbergen and running parallel to the west coast of Spitzbergen 
and a north-south oriented ice edge at the southern tip of Spitzbergen. The boundary 
layer front appeared where the northerly air flow from the ice cap modified by the rela- 
tively warmer ice free water meets the unmodified cool air flowing from the cold 
ice/snow covered Spitzbergen and sea ice to the south. The narrow tongue of warm 
water from the Norway Current that runs in Fram Strait adds to the boundary layer 
forcing. The frontal structure was determined from dropsonde data (Fig. 15). A low- 
level jet is clearly depicted in Shapiro and Fedor's cross section of the boundary layer 
front in Fig. 15. Fett (1989a) proposes that the low-level jet is caused by thermal wind 
forcing between the surface temperature gradient from the open sea to the ice-covered 
land. The low-level jet is a result of a secondary thermally direct circulation where the 
air is being returned toward the land at the upper levels. Shapiro and Fedor (1989) 
found that the thermal gradient above the low-level jet was in the opposite direction of 
the horizontal gradient in the boundary layer front. This then supports Fett's hypothesis 
of a return flow to land or ice covered surfaces at upper levels. The boundary layer front 
in this case extends to 850 mb. The surface inversion west of the front is deeper due to 
convective overturning by turbulence in the boundary layer. There is also a strong sur- 
face inversion over Spitzbergen and the ice pack due to radiational cooling. Shapiro and 
Fedor (1986) found large values of relative and potential vorticity along the front. 



21 



700 - 



3 
W 
ID 
w 900 

tr 

Q. 



1000 




gSsissBaca S m aaBMBBM 



SONDE 12 SONDE t3 

■ ♦ ' i lL 



SONDE M 

jjL 



12° 13° 



15° 16° 17° 18° 19° 20° 21° E 



Fig. 15. Vertical cross-section of a boundary layer front (from Shapiro and Fedor 
1989) 

Fett (1989b) observed a westward propagating boundary layer front that formed 
in Fram Strait on 25 March 1987. The front was embedded in north-south oriented 
cloud streets with colder air to the east and relatively warmer air to the west. Along the 
front multiple vortices were observed with the largest vortices located at the southern 
end. Unlike Shapiro and Fedor (1986) case, the surface inversion was higher east of the 
front and extended to 2 km. East of the front the boundary layer was only 1 km. 

Vortex generation plays an important role in boundary layer fronts. Fett 
(1989b) proposes that the vortices that form due to boundary layer fronts can generate 
into polar lows under certain conditions. The boundary layer front is thought to pre- 
condition the lower levels for polar low development but other factors must be present. 
Cold air aloft and upper level support in the form of a 500 mb trough or low is needed. 
In addition low-level baroclinicity and vorticity is required. Fett (1989b) observed that 
on 12 December 1982 in the Norwegian Sea a polar low formed at the southern end of 
a boundary layer front. Shapiro and Fedor (1989) also cited the formation of a polar 
low on the southern end of boundary layer front on 19 April 1985 south of Spitzbergen. 
4. Cloud Features in Satellite Imagery 

An extremely useful Navy Tactical Applications Guide for satellite imagery was 
recently published for the Arctic (Greenland/Norwegian/Barents Seas) by the Naval 
Environmental Prediction Research Facility (Fett 1989a). This guide uses high resol- 
ution satellite data to illustrate significant cloud patterns in the Arctic. 
a. Surface Streamlines 

Streamline analysis using satellite imagery is a useful tool in the Arctic 
where surface observations are sparse and satellite imagery may be the primary data 



22 



source. Identifying troughs and ridges through cloud types is the first step. Overcast 
stratus, stratocumulus, or fog, are associated with anticyclonic flow. Ridge lines appear 
in clear or very thin, shallow, fog areas with weak winds. Cyclonic or straight flow is 
characterized by open cell or stratocumulus clouds. Col areas are regions where the 
wind curvature changes drastically over a small distance (Fett 1989a). Cloud streets are 
indicative of ofT-ice flow and can be used to clearly draw streamlines. Clear conditions 
in the MIZ also indicates off-ice flow. 

b. Arctic Fronts 

An Arctic front is a disjointed band of low and high level cloudiness that 
moves southward in association with an outbreak of a cold Arctic air mass. Enhanced 
satellite imagery and a practiced eye are needed to detect and monitor Arctic fronts. 
Fig. 10-1 la in Fett (1989a) depicts a well defined Arctic front. Cloud plumes form when 
strong low-level winds encounter elevated terrain. When cyclonically curved cloud 
streaks or banded cloudiness align with these observed cloud plumes, an Arctic front 
may be indicated. Mountain waves form when high winds are orographically lifted and 
this can be another indication of an Arctic front location. 

c. Polar Lows 

Polar lows often develop within open-celled cumulonimbus. The lows have 
a comma or spiral shaped cloud pattern and some may have a clear eye. Elongated 
bands of cloud clusters that lead into low pressure centers with strong convective activity 
are a favorable region for polar low development. Multiple polar lows may form in this 
type of region. The life span of a polar low may be as short as 6 hours or last 2 to 3 
days and therefore satellite imagery must be monitored every 1 to 2 hours for polar low 
detection and tracking. Two other favorable regions for development are in the cold air 
masses behind Arctic fronts and in the vortices at the southern end of boundary layer 
fronts. 



23 



III. SYNOPTIC OVERVIEW OF PHASE I 

A. DATA SOURCES 

Information for describing the synoptic and mesoscale conditions of Phase I were 
derived from several sources. The R/ V Polarbjoern provided the most continuous and 
frequent surface and upper air data. A buoy array deployed in the drift region for the 
experiment provided reasonably continuous but limited surface data. The synoptic scale 
fields were based on operational surface and upper air reports and hemispheric predic- 
tion models. Meteorological satellite imagery was used to verify the synoptic scale an- 
alyses and match them to the in situ measured data. 

1. R/V Polarbjoern 

Surface layer vector wind, air temperature, humidity, and surface pressure were 
recorded for 10-minute intervals on the R/V Polarbjoern. The system used for the 
measurement and initial signal processing was the Coastal Climate WeatherPak 
meteorological weather station. The 10-minute average values, and gust and variance 
statistics with the periods were calculated with a micro-computer based acquisition sys- 
tem. At least twice daily rawinsondes launched from the ship provided vertical profiles 
of temperature, humidity, and wind speed and direction at mandatory and significant 
pressure levels. The R/V Polarbjoern' s track during the drift phase is depicted in 
Fig. 16. The position of the ship at the beginning of the experiment and on the 10th 
and 20th of each month were plotted. The thick black lines represent the position of the 
ice edge obtained from the NPOC weekly analyses. The analyses are based on data from 
21 September, 19 October, 16 November, and 21 December 1988 with the ice edge ana- 
lyzed further south each month. 

2. Surface Buoys 

Surface layer temperature and pressure were measured from six buoys that were 
deployed in an array around the R/ V Polarbjoern. The initial array pattern appears in 
Fig. 16. as well as each buoy's position on the 10th and 20th of each month. The 
measured values as well as position were relayed to a polar orbiting satellite within the 
Argos network. Argos is a French-designed sensor located on a polar orbiting satellite 
that collects environmental data. Data is acquired by the satellite as it passes over the 
buoy. The Argos system has been tested to be locationally accurate to within 50 meters 
(Rao et al. 1990). 



24 



6 3'JOW 



80* N 



79*3 ON 



7»'iOH 




10* E 12' E 14* E IS*E 1B*E 20* E 22* E 



2« E 26 E 



Fig. 16. Buoy array and R/V Polarbjoern positions during drift phase for dates 
September 20 to January 7: buoys are denoted by numbers 1-6, ship is 
denoted by a P, and ice edge analyses are represented by thick black lines. 



25 



The Pacific Marine Environmental Laboratory (PMEL) received the buoy data, 
processed into pressure and temperature information, and then averaged the data into 
hourly data sets. There were no gaps greater than three hours. Buoy 1 was deployed on 
16 September and transmitted data until 19 November. All the buoys, except buoy 1, 
transmitted data through Phase I. Buoy 3 was also deployed on 16 September. Buoys 
2, 4, 5 and 6 were deployed on 17 September. The buoy array translated and changed 
it configuration during the drift period as shown in Fig. 16. The lighter lines depict the 
individual buoy tracks. The symbols represent the buoy positions on the 1st, 10th, and 
20th of each month. 

3. Surface and Upper Air Reports and Global Analyses 

The approach in analyzing meteorological features during Phase I was to use 
available land and ship observations and satellite imagery. Fewer upper air reports were 
available in the region, so the emphasis shifted to the upper air analyses from Naval 
Operational Global Atmospheric Prediction System (NOGAPS) which were used in 
conjunction with information on the satellite images. Satellite imagery, above all, 
proved indispensable in the Arctic as the number and frequency of weather reports in 
the region is sparse. 

The number of stations reporting surface and upper air meteorological data for 
synoptic scale descriptions within the region are few but not as scarce as for an open 
ocean region. Information form these stations, of course, are used to make the analyzed 
and predicted fields which were the basis for describing synoptic scale conditions. 
Fig. 17 depicts the reporting stations on a synoptic map for the eastern part of the 
Arctic Circle. Table 1 lists the names and locations of some of the stations. The WMO 
code is the two number country block code and three number station identifier. The 
station's actual reports, listed in columns five and six, are only for the period covered 
during Phase I of CEAREX. The Norwegian community on Svalbard reports as station 
01008 not 01005 or 01007. The Greenland station 04340 did not report, but another 
station, 04339, not on the chart, did report. Of the Greenland stations only 04320 and 
04339 reported with any regularity, and only one station, 04320, located on the east- 
northeast Greenland coast, reported upper air observations. Of the Norwegian stations, 
Bear, Hopen (Hope) Island and Svalbard reported frequent surface observations as well 
as those located on mainland Norway. Only Jan Mayen and Bjornoya (Bear) Island 
produced upper air reports. All the U.S.S.R. stations frequently transmitted surface 
observations, and all but one frequently transmitted upper air observations. There are 



26 



many other WMO stations listed on the synoptic map but no data was received from 
those stations during this period. 



Table 1. REPORTING STATIONS, LOCATION, 


AND DATA REPORTS 


Country/Station Name 


WMO 
Code 


Latitude 


Longi- 
tude 


Surface 
Reports 


LA 
Re- 
ports 


GREENLAND 












Nord 


04310 


81.36N 


16.40W 


X 


— 


Danmarkshaven 


04320 


76.46N 


18.40W 


X 


X 


Danebord 


04330 


74.18N 


20.13W 


X 


— 


Scoresbysund 


04339 


70.29N 


21.58W 


X 


— 


Kap Tobin 


04340 


70.25N 


21.58W 


— 


— 


NORWAY 












Jan Mayen 


01001 


70.57N 


08.40E 


X 


X 


Isfjord Radio, Svalbard 


01005 


78.43N 


13.38E 


— 


— 


Longyearbyen, Svalbard 


01007 


78.13N 


15.35E 


- 


- 


Svalbard 


01008 


78.15N 


15.28E 


X 


— 


Bjornoya Island 


01028 


74. 3 IN 


19.01E 


X 


X 


Hopen Island 


01062 


76.30N 


25.04E 


X 


— 


Hammerfest Aeradio 


01053 


70.45N 


23.41E 


— 


— 


Fruholmen fyr 


01055 


71.05N 


24.00E 


X 


— 


Sletnes fyr 


01078 


71.05N 


29.14E 


— 


— 


L.S.S.R. 












Kheysa Ostrov, Franz Joseph 


20046 


80.37N 


58.03E 


X 


X 


Vize Ostrov 


20069 


79.30N 


76.59E 


X 


X 


Barencburg, Svalbard 


20107 


78.04N 


14.13E 


X 


X 


Mys Zhelaniya, N. Z. 


20353 


76.57N 


68.35E 


X 


X 


Russkaya Gavan, N. Z. 


20357 


76.11N 


63.34E 


X 


— 



Synoptic scale conditions were interpreted from fields generated at two 
meteorological centers, the Navy's Fleet Numerical Oceanography Center (FNOC) and 
the National Meteorological Center (NMC). FNOC's NOGAPS model surface analyses 
were compared with the National Meteorological Center's (NMC) final hand analyzed 



27 




ICE IEGEND 



E.lrcnve l.m.i to. Seo !<• In AUGUST 
ElH«mt limil Fd> S*c lc. In FEttUADV 



Fig. 17. Synoptic map of eastern Arctic Circle showing reporting stations. 

surface analyses and satellite imager}'. The 700 mb, 850 mb, and 500 mb upper air fields 
used were available from NOGAPS. 

NOGAPS is the Navy's current numerical weather prediction model for use over 
the Arctic as well as the globe. NOGAPS version 3.0 was in use during Phase I of 
CEAREX. NOGAPS uses a six hour (or twelve if six is not available) forecast for its 
first guess. The first guess is used at a grid point where there are no data. In the Arctic, 
where there is limited data, the model relies heavily on its six (or twelve) hour forecasts. 
The six (or twelve) hour forecasts in turn rely heavily on previous forecasts. This can 
cause significant problems when unexpected and rapidly developing systems occur. 



28 



NOGAPS grid resolution is not fine enough to resolve boundary layer fronts and most 
polar lows. 

NMC's Northern Hemisphere surface analyses are subjectively generated four 
times a day. All available surface reports, satellite imagery, ship reports, buoy reports, 
and upper air observations are used. Consequently, the NMC hand drawn final analyses 
depict fronts and other features better than NOGAPs model analyses. NMC analyses 
showed much greater detail in the Arctic and picked up mesoscale features which are not 
possible with NOGAPS due to the resolution of the model. 
4. Meteorological Satellite Imagery 

The meteorological satellite imagery used are from the National Oceanic and 
Atmospheric Administration (NOAA) 9, 10, and 11 satellites and the Defense 
Meteorological Satellite Programme (DMSP). The NOAA imagery are from the Ad- 
vanced Very High Resolution Radiometer (AVHRR) High Resolution Picture Trans- 
mission (HRPT) sensors on board the satellite and has a resolution of 1 km by 1 km. 
Most of the enhancements were done at Tromso, Norway using Channel 4. The re- 
mainder of the enhancements were conducted using tapes supplied by Tromso on the 
computers at the Naval Postgraduate School and Naval Oceanographic and Atmo- 
spheric Research Laboratory Administrative Directorate (NOARL-AD), both located 
in Monterey, California. 

Channels 1 (.58 - .68 /im) and 2 (.73 - 1.1 /jm) detect visible and near infrared 
solar radiation and could not be used in this thesis due to insufficient sunlight within the 
Arctic basin during this time period. Channel 3 (3.55 - 3.93 /xm) detects both emitted 
and reflected solar radiation. If there is an imbalance of sunlight in the satellite pass, 
channel 3 must be used with care. Channels 4 (10.3 - 11.3 xxm) and 5 (11.5 - 12.5 /xm) 
both provide thermal mapping of clouds and surface features with channel 5 accounting 
for water vapor attenuation. In the Arctic where the atmosphere is very dry, the differ- 
ences between channels 4 and 5 were not discernable. The DMSP mosaics were com- 
piled by NOARL-AD and used to supplement NOAA satellite imagery. The DMSP 
infrared mosaics have a resolution of approximately 4.0 km. 

The satellite imagery was especially useful in detecting sub-synoptic and short- 
lived systems which are not resolved or handled well by numerical models and frequently 
missed by hand analyses. Cyclogenesis in the Arctic was only observed through satellite 
imagery and land observations. Neither NOGAPS nor NMC detected this event in the 
Arctic. 



29 



B. GENERAL SYNOPTIC FEATURES 

The meteorological fields were analyzed for the eastern Arctic Circle from Greenland 
east through Novaya Zemlya and north of Iceland to the central Arctic Ocean. The 
Arctic Circle is defined as north of 66°N. The Arctic basin or Arctic Ocean encompasses 
the area north of 80°N. NOGAPS upper level analyses, NMC surface analyses, satellite 
imagery, drifting buoy, land and ship observations were used. The mean and anomaly 
charts referenced in this study for sea level pressure, 500 mb geopotential heights and 
1000-500 mb thickness were compiled by the Climate Analysis Center of NOAA. The 
meteorological conditions at the ship were analyzed using time series of all the surface 
data collected. Time series of the surface pressure, wind speed and direction, and tem- 
perature measured on the R/V Polarbjoern from September 1988 to early January 1989 
give a good synopsis of the surface meteorological variability at the Rj V Polarbjoern 
during Phase I of CEAREX. 

1. September 1988 

The mean northern hemisphere sea level pressure analysis for September 1988 
(Fig. 18a) shows the dominance of a low pressure center over the central Arctic basin. 
High pressure exists over the Canadian Archipelago with ridging east across Greenland 
to Svalbard. The northern hemisphere sea level pressure anomaly chart (Fig. 18b) de- 
picts lower than average sea level pressures for the central Arctic basin. The northern 
hemisphere 500 mb mean geopotential heights (Fig. 19a) reflect the persistence of a 500 
mb low height center over the central Arctic basin throughout September defining the 
center of the circumpolar vortex. The anomaly chart (Fig. 19b) reflects that the heights 
are significantly lower than average over the central Arctic and through the Greenland 
and Norwegian Seas. Higher heights than average exist over Greenland. The northern 
hemisphere 1000-500 mb anomaly thickness chart (Fig. 20b) shows slightly cooler tem- 
peratures over the central Arctic basin but slightly warmer temperatures in the 
Greenland Sea. 



30 



1 

° go; 4 




Fig. 18. a) Mean and b) anomaly sea level pressure for September 1988 (Climate 
Analysis Center 1988a) 







k ^^^ «L X 






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a 




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Fig. 19. a) Mean and b) anomaly 500 mb geopotential heights for September 1988 

(Climate Analysis Center 1988a) 



31 







Fig. 20. a) Mean and b) anomaly 1000-500 mb thickness for September 1988 (Cli- 
mate Analysis Center 1988a) 

A 500 mb low height center over the central Arctic basin dominates September 
weather as reflected in the 500 mb mean geopotential heights chart (Fig. 19a). The key 
synoptic events of the month are now reviewed. On 17 September, a low height center 
in the central Arctic basin has a trough extending south, west of Greenland, and a 
trough extending south, over Franz Joseph Land and Novaya Zemlya. In the next few 
days, the 500 mb low height center deepens and moves into the eastern Arctic basin with 
the associated long wave trough moving east across Greenland, Fram Strait, and 
Svalbard. The 500 mb height center then moves south into northern U.S.S.R. and fills. 
A second low height center forms over the western Arctic basin and associated troughing 
extends south over Greenland and Norwegian Seas, and Svalbard the later part of the 
month. 

On 17 September a surface quasi-stationary high pressure center over the 
Canadian Archipelago ridges east across Greenland to Svalbard. A 984 mb low pressure 
center is in the western Arctic basin. By the 20th, the surface low pressure center over 
the Arctic, moves east, north of Svalbard, which decreases the surface pressure in the 
area, but a weak pressure gradient exists. The low pressure center moves south, then 
southeast through the Barents Sea. High pressure ridging east over Greenland Sea and 



32 



Svalbard resumes from the high pressure that remains over Greenland for the remainder 
of the month. Two low pressure systems move northeast along the coast of Norway, 
but do not reach farther north than 70°N. 

The time series from the R/V Polar bjoern for September (Fig. 21) shows rela- 
tively steady pressure changes at the ship with no sharp pressure increases or decreases. 
The only significant drop in pressure occurs when the low pressure system over the 
central Arctic basin migrates south over Northeast Land then moves southeast to 
Novaya Zemlya on the 20th. Winds are predominately from the northwest to west in 
response to the strong ridging over Greenland. The southerly winds from 18 to 20 Sep- 
tember occur when the central Arctic low migrates south to the ship's position. By the 
evening of the 22nd, the low pressure system is east of the ship and west-northwest winds 
resume. Speeds range from calm to 10 msr\ but usually are 5 ms~ x or less. Air tem- 
peratures range from to — 20°C with a general cooling trend noted during the month. 




> »• 



3 „ 



tiai >— 



uu(^.j^^ ,. 






Li i« n e tfioiiiiUiiliil 



Fig. 21. R/V Polarbjoern time series for September 

2. October 1988 

The mean northern hemisphere sea level pressure pattern for October 1988 
(Fig. 22a) shows low pressure dominating the northern Arctic circle shifting to near the 
U.S.S.R. and high pressure dominating the Greenland, Norwegian and Greenland Seas, 
and Svalbard region. The anomaly sea level pressure chart (Fig. 22b) shows pressures 
lower than average over Severnaya Zemlya and Novaya Zemlya. Higher pressures than 
average are over the Greenland Sea, Fram Strait, Svalbard and Norwegian Sea. This 
produces a tight gradient east of Svalbard over the Barents Sea. The mean northern 
hemisphere 500 mb geopotential heights (Fig. 23a) illustrate the low height center over 



33 



the central Arctic which has strengthened from September's analysis. Lower heights 
over Greenland are evident which produces a tight gradient in the south Greenland Sea. 
This gradient is much tighter than September. The northern hemisphere 1000-500 mb 
thickness chart (Fig. 24a) depicts the coldest air over the central Arctic. The anomaly 
thickness chart (Fig. 24b) shows colder temperatures than the average over Svalbard 
and Franz Joseph Land. East of Greenland, the layer is much warmer than average, 
which sets up a stronger temperature gradient than normal in Fram Strait and 
Norwegian Sea. 



' / \ 


-ej 


^ 










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a 


17 A 




^s*4 — — ia\ 






b 




JZA^r^* ■ 







Fig. 22. a) Mean and b) anomaly sea level pressure for October 1988 (Climate 
Analysis Center 1988c) 



34 




Fig. 23. a) Mean and b) anomaly 500 mb geopotential heights for October 1988 

(Climate Analysis Center 1988c) 




Fig. 24. a) Mean and b) anomaly 1000-500 mb thickness for October 1988 (Climate 
Analysis Center 1988b) 



35 



October has significantly more cyclone activity than September and is related 
to the stronger westerlies over the CEAREX area shown in the mean 500 mb 
geopotential heights chart (Fig. 23). In the beginning of October, troughing at 500 mb 
weakens over Svalbard and zonal flow commences. A low height center exists over the 
central Arctic basin with a weak short wave trough establishing over the east Greenland 
coast on the 6th. By the 8th, the trough deepens and moves east across Fram Strait. 
At the same time, the low height center over the central Arctic basin moves east north 
of 80°N between Greenland and Svalbard and deepens from 4969 meters to 4746 meters 
from 7 to 10 October. A short wave trough extends south from the low height center 
over Fram Strait through the Norwegian Sea. On the 10th, the height center begins to 
fill and move westward over northwest Greenland. By the afternoon of the 12th, a low 
height center forms north of Svalbard with troughing extending south from Svalbard to 
Norway. This event will be analyzed further in Chapter IV. The low height center 
moves east north of 80°N between Svalbard and Franz Joseph Land and remains with 
steady height values of 5901 meters early on the 13th. The low height center tracks east 
toward Franz Joseph Land and on the 14th begins to fill and move southeast toward 
northern U.S.S.R. Low heights resume over the central Arctic basin for the rest of the 
month. 

At the lower levels satellite imagery on the 10th shows a developing mesoscale 
vortex forming over Spitzbergen and a second one over Northeast Land. A boundary 
layer front forms in Fram Strait which will be further studied in Chapter IV. The verti- 
cally stacked low pressure system that tracks into the Arctic basin and then tracks west, 
north of Greenland is visible in the NOAA satellite imagery on the 10th. By the after- 
noon of the 10th the vortex over Northeast Land moves north over the ice pack bringing 
southerly winds to the ship and low level warm air advection. The polar low over 
Spitzbergen dissipates. The northern portion of the boundary layer front is beginning 
to form a vortex which develops into a polar low in subsequent satellite images. Late 
on the 10th, DMSP imagery shows a well developed polar low in Fram Strait. Through 
9 and 10 October the low pressure pattern is producing strong southerly flow in the vi- 
cinity of Svalbard. Satellite images over Svalbard on the 11th show multi-level 
cloudiness in strong cyclonic flow. By late evening on the 1 1th, a narrow band of clouds 
extends south from the Arctic Circle over Svalbard and extends into the northern por- 
tion of the Norwegian Sea. By the morning of the 12th, strong low level cyclonic turning 
is evident in Fram Strait by satellite imagery. Widespread multi-level cloudiness exists 
over Northeast Land and north through the eastern Arctic basin. Upper level 



36 



cloudiness through the 12th obscures the detection of the formation of the surface low 
pressure system. This development is the subject of a case study in Chapter IV. The 
morning of 13 October, the low pressure system is clearly visible as a well vertically de- 
veloped cyclone. The cyclone moves east producing strong northwest winds behind the 
system in the vicinity of Svalbard. The vertically stacked low pressure system tracks east 
to Franz Joseph Land and begins to fill. Surface high pressure dominates Svalbard 
weather with light to moderate winds and variable directions. A low pressure system 
moves northeast from Iceland along the MIZ from 16 to 18 October but rapidly dissi- 
pates east of Svalbard over the advancing pack ice. Weak surface high pressure gradi- 
ents dominate the weather the remainder of the month. 

In October surface pressure at the ship (Fig. 25) decreases from 1008 mb to a 
low of 959 mb early on the 9th as a surface low pressure system rapidly tracks from 
Norway north-northeast, passing east of Kvitoya into the central Arctic basin. A second 
sharp pressure decrease occurs on the afternoon of the 12th and persists through the 
13th. as a low forms over the ship and remains quasi-stationary for 24 hours, then 
tracks southeast to Novaya Zemlya. A more modest decrease in pressure on the 19th 
occurs when a low pressure trough extending south from a low over the central Arctic 
tracks eastward across Svalbard to Franz Joseph Land. The remainder of the month is 
dominated again by high pressure ranging from 1010 to 1020 mb. The wind direction 
is more variable this month from 6 to 20 October as the low pressure centers and the low 
pressure trough that pass through the region produce southerly winds in advance of the 
passage and then west-northwest winds after passage. Speeds above 10 ms -1 occur from 
8 to 15 October with a period of 15 to 20 mr 1 on 12 and 13 October. After 20 October, 
winds are generally less than 10 ms~ x and from the northerly direction. Air temperatures 
are steady around — 20°C until the 12th, when a sharp warming occurs (— 24°C to 
— 8.1°C) with a 16 C C increase in temperature. The rest of the month air temperatures 
average — 20°C with a general cooling trend to — 25°C occurring near the end. 



37 






•\*/v\ /M* 



^MT,' 






VAw 




Fig. 25. R/V Polarbjoern time series for October 

3. November 1988 

The northern hemisphere mean sea level pressure pattern for November 1988 
(Fig. 26 a) shows the dominance of low pressure over the Arctic basin from Svalbard 
to Novaya Zemlya in the Barents Sea. The anomaly sea level pressure pattern (Fig. 26 
b) reflects the tight gradient along 15°E as higher pressures than average exist over 
Greenland Sea and lower pressures are over Novaya Zemlya producing a strong gradient 
in the Barents Sea and Svalbard. The northern hemisphere 500 mb geopotential heights 
(Fig. 27 a) shows two weak low height centers, one over Franz Joseph Land/Novaya 
Zemlya, and one over the Canadian Archipelago. The anomaly 500 mb geopotential 
height chart (Fig. 27 b) shows lower heights than average over Novaya Zemlya, Barents 
Sea, and Svalbard and higher heights in the Greenland Sea. The 1000-500 mb thickness 
chart (Fig. 28 a) reflects colder temperatures for November than October. A colder 
pool of air than average over Svalbard and warmer temperatures exist over Greenland 
is reflected in the anomaly thickness chart (Fig. 28b). 



38 




Fig. 26. a) Mean and b) anomaly sea level pressure for November 1988 (Climate 
Analysis Center 1988c) 




Fig. 27. a) Mean and b) anomaly 500 mb geopotential heights for November 1988 

(Climate Analysis Center 1988c) 



39 




Fig. 28. a) Mean and b) anomaly 1000-500 mb thickness for November 1988 (Cli- 
mate Analysis Center 1988c) 

November has very little significant cyclonic activity due to the strength of the 
circumpolar vortex as reflected in the anomaly thickness chart (Fig. 28b). The 500 mb 
NOG APS analyses show a low height center over Severnaya Zemlya the first part of the 
month and a second low height center over the Canadian Archipelago. No significant 
troughing or low height center moves near Svalbard or Fram Strait. 

At the surface, no significant weather features occur in November. The low 
pressure systems that do move into the region are weak. High pressure in the beginning 
of the month produce light and variable winds which gives way early in the month to a 
tight pressure gradient which produces strong northerly winds the remainder of the 
month. Strong northerly winds existed over the ship for almost the entire month of 
November as a result of the strong pressure pattern as seen in the mean sea level pres- 
sure pattern (Fig. 26a). Satellite imagery confirms the strong northerly flow off the ice 
sheet east of Svalbard and strong easterly and northerly winds in Fram Strait. One in- 
teresting satellite feature visible on NOAA imagery (Fig. 29) is a strong quasi-stationary 
Arctic front that is visible over Svalbard on the 14th along the MIZ. The Arctic front 
represents a sharp boundary between the cold pool of central Arctic air and the warmer 
air from the North Atlantic. 



40 




Fig. 29. NOAA-11 Satellite imagery on 140810Z November 1988 

No significant weather features occurred at the ship in November as seen in the 
time series for that month (Fig. 30). Strong southerly winds (10 msr ] ) on 6 and 7 No- 
vember occurred which caused temperatures to rise from — 30°C to a high of — 15.4°C. 
Southerly winds sustained temperatures in the high teens through the 11th. Northerly 



41 



winds (5 to 12 mr 1 ) brought a persistent cooling trend until the end of the month. No 
sharp pressure changes were noted for the entire month. Pressure ranged from 1010 to 
1020 mb. 



J 



■n ,, ;> ^^^ rv ^^^HA# 



,Jv- 



Fig. 30. R/V Polarbjoern time series for November 

4. December 1988 to 7 January 1989 

The northern hemisphere mean sea level pressure pattern for December 1988 
(Fig. 31a) continues to show a low over the eastern Arctic basin between Svalbard and 
Severnaya Zemlya. The anomaly sea level chart (Fig. 31b) shows much lower than av- 
erage pressures over the central Arctic, Barents, Greenland, and Norwegian Seas. The 
mean 500 mb geopotential height chart (Fig. 32a) shows a low height center between 
Svalbard and Severnaya Zemlya. The heights are significantly lower than average in the 
Arctic and Greenland Sea. The 1000-500 mb thickness anomaly chart (Fig. 33b) depicts 
a significantly colder pool of air than average from northeast Greenland to Novaya 
Zemlya. The colder air and lower heights than average increase the amount of cyclonic 
activity that occurs in December. 



42 



v jc / y X 


'^S537^ >( 




/\ - 


y \ "* 


\ \jy~M f~\z-*~~^^ 




/ \ 




^^^B 








^^51^7^ 


'$y^\7 




flTTr/iMf^ 






Nyy 


u r 






^^Fu 




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(74I /I 4 A ^rTNVV^vOCy 






/ \ 


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—1 










Sxf // 




»(—-"*' / 




a /" 


! iW^^jg^j, \ 






b / 


^*^^i/L ~\&^K 













Fig. 31. a) Mean and b) anomaly sea level pressure for December 1988 (Climate 
Analysis Center 1988d) 




Fig. 32. a) Mean and b) anomaly 500 mb geopotential heights for December 1988 

(Climate Analysis Center 1988d) 



43 




Fig. 33. a) Mean and b) anomaly 1000-500 mb thickness for December 1988 (Cli- 
mate Analysis Center 1988d) 

The average 500 mb statistics show a 500 mb low height center dominating the 
eastern Arctic basin. NOGAPS 500 mb height pattern the beginning of December de- 
picts a short ridge in the Greenland Sea which moves east as a short wave enters the 
Greenland Sea on the 2nd. The short wave extends northwest to southeast across the 
Greenland Sea and Fram Strait. By the 3rd, the flow in the region becomes zonal and 
then ridging from northern Europe moves in east of Svalbard extending to the Arctic 
basin. On the 7th, the low height center over northern Greenland moves east-southeast 
into the Greenland Sea. This path is a secondary track according to the literature 
(Serreze and Barry 1988). The low height center continues to move east across Svalbard 
on the 8th deepening by 80 meters. The height center then moves north of 80°N, starts 
to fill, tracks slowly east, then north to the center of the Arctic circle where it stagnates. 
Ridging north from the North Atlantic moves over Greenland and Norwegian Seas and 
vicinity of Svalbard. A short wave trough digs south into Greenland and Norwegian 
Seas on the 16th and moves east. Weak troughing in the region persists until the 30th. 
Strong ridging north over east coast of Greenland moves slowly east over Svalbard. A 
deepening low height center moves east across Greenland into the Greenland Sea by 2 
January. The low height center then tracks east across Svalbard on the 3rd. By the 4th 



44 



ridging over Norwegian and Greenland Seas from northern Europe resumes until the end 
of the period. 

A review of surface pressure events indicates a low pressure center (1 December) 
located over the Greenland ice sheet deepens and tracks northeast entering the 
Greenland Sea early on the 2nd. The low remains steady and tracks east across Svalbard 
then northeast into the central Arctic basin where the low begins to slowly fill and move 
in erratic tracks. On the 4th a low pressure center over Iceland moves northeast into the 
Norwegian Sea and then tracks east south of Svalbard and along the east-west oriented 
MIZ and slowly fills. High pressure ridges north over Fram Strait and Svalbard com- 
mencing at 061200Z. A low pressure center over north Greenland begins to track east 
early on the 7th, deepens, and moves rapidly east across Greenland Sea to southern 
Svalbard by the 8th. The low continues to deepen and moves east along 80°N over 
Franz Joseph Land. High pressure ridging east across Greenland Sea, Fram Strait, and 
Svalbard behind the low pressure center occurs on the 10th. This ridging is replaced by 
ridging north from northern Europe. Weak low pressure begins to break down the 
northward ridging over Svalbard. High pressure center over north Greenland resumes 
its eastward ridging across Greenland Sea, Fram Strait, and Svalbard. Tight surface 
gradients produce strong northerly winds. On 1 January high pressure over northern 
Europe resumes it northward ridging over the region. A deepening low pressure system 
tracks from northeast Greenland east south of 80°N over Svalbard on the 2nd. The low 
then tracks east to Franz Joseph Land by the afternoon of the 3rd, then southeast to 
Novaya Zemlya. High pressure resumes over the region through the end of Phase I. 

December brought many changes as evidenced in the ship's time series 
(Fig. 34). The passage of two cyclones on the 3rd and 9th brought significant changes 
in the weather pattern. December's average temperature was higher than expected due 
to the passage of the two cyclones which produced two sharp temperature increases 
which lasted from one to two days. On 30 November, southerly winds started a gradual 
warming near the ship where temperatures rose from — 30°C to — 3.3°C in three days. 
After the passage of the first cyclone, northerly winds resumed and the temperatures 
rapidly decreased to the high negative twenties. A minimum pressure of 957 mb oc- 
curred late afternoon on the second of December. The southerly winds ranged from 10 
to 15 msr\ The northerly winds after storm passage were much stronger ranging from 
12 to 17 msr 1 on the fourth of December. The wind changed direction again on the 7th 
to the southerly direction with the approach of the second cyclone with maximum speeds 
recorded at 16 msr 1 . Air temperatures again rose to — 3°C with a 24°C temperature in- 



45 



crease in less than 18 hours. Winds from the southerly direction maintained high tem- 
peratures through the 8th. Winds changed to northeast early on the 9th and 
temperatures decreased. Minimum pressure of 954 mb occurred on the morning of the 
eighth. From the 11th, winds were highly variable with averages of 6 msr x from 11 to 
20 December and less than 5 mr* until the end of the month. Temperatures gradually 
dropped to — 35°C in late December. No significant variations in pressure were observed 
during the later part of the month with a range of 990 to 1010 mb. 

Early January brought another cyclone with minimum pressure recorded at the 
ship of 956 mb on the night of the 2nd. Light to moderate southerly winds brought a 
sharp temperature increase from — 30°C to — 1°C midday on the 2nd. Winds peaked at 
14 rns -1 late on the afternoon of the 2nd from the south. Winds stayed from the 
southerly direction through the early evening of the third. At that time, strong (15 
mr x ) northeasterly winds commenced which cooled the air temperature to — 25°C. 
Moderate northerly winds (8 to 12 ms~ l ) persisted through the 7th when the ship began 
its transit to Tromso, Norway. 




,^-* r "~ A ^^S^Ito /T^ /y^~^ 



S^/^V^j^yW*^,^ 



f\i\ \ La 





: j • s 4 ' t i i: i i. u u u ii r it r :. ii a ij i. u ji r a » jc j' i 1 > i t • • • » 



Fig. 34. R/V Polarbjoern time series from 1 December to 10 January 

5. Summary 

The wind speed at the ship was highly variable ranging from periods of calm to 
periods with winds as high as 20 mr 1 . The higher winds throughout the time period 
were associated with the passage of Arctic cyclones with moderate southerly winds 
ahead of the cyclone followed by strong persistent northwesterly winds after passage. 
The persistence of the north-northwest winds during Phase I steered the ship east of 
Svalbard. The strong cyclone activity to the east over Novaya Zemlya and ridging over 



46 



Greenland (illustrated in the ship's November pressure field) explain the ship and ice 
movement. Climatology suggested that northeast rather than northwest winds would 
dominate and the drift of the ship was to be southwest, west of Svalbard in Fram Strait. 

The air temperatures ranged from 0°C to -35°C, with each month's average 
temperature decreasing 5 to 7 °C as winter approached. Dramatic temperature rises of 
15 to 25°C occurred with the six major cyclone passages during the experiment. 

The number of cyclones was significantly higher than what is expected for the 
climate of the region as evidenced by the 500 mb geopotential height and sea level 
pressure anomalies for October and December. Most of the significant weather features 
occurred in October, December, and early January. The storm that formed near the ship 
early on 12 October will be closely studied and contrasted with the storms that passed 
on 9 October, 2 and 8 December 1988, and 2 January 1989 along with other minor low 
pressure systems. 

As Serreze and Barry (1988) noted in their climate study, cyclone tracks are 
subjective. The autumn and early winter period in this study represented a very large 
variability in both the number and direction of cyclones entering the Arctic basin. Most 
of the storms during Phase I of CEAREX, except for the cyclogenesis event on 12 Oc- 
tober, represented the climatic principle and secondary cyclone tracks. The storms 
trajectories were very variable and followed the climate studies conducted by Gorshkov 
(1983) rather than Serreze and Barry (1988) as outlined in Chapter II. Gorshkov (1983) 
shows a large variability in cyclone trajectories for each month as well as from month 
to month which were corroborated in this study. 

Each cyclones trajectory during the drift phase of CEAREX is illustrated in 
Fig. 35. All but one of September's cyclones tracked northeast along the west coast of 
Norway and then east across the southern Barents Sea. A low pressure system on the 
20th migrated from the central Arctic basin south over Northeast Land and then 
southeast to Novaya Zemlya. This is an unusual trajectory for a cyclone. Gorshkov 
(1983) depicts a secondary cyclone track from north of Greenland within the Arctic 
basin to southeast Barents Sea in his January and February climatic cyclone charts 
(Fig. 10c and d). However, even these tracks do not show the cyclone as originating 
from the central Arctic basin like the 20 September cyclone. 



47 




qAQsfr- 



Fig. 35. Cyclones Tracks for Phase I of CEAREX: September (solid); October 
(dashed); November (dotted); December (dot-dash); and January (dot- 
dot-dash). 

The cyclone that passed east of the R/V Polarbjoern on 9 October originated 
from the North Atlantic and moved northeast along the Norwegian coast, then tracked 
rapidly north-northeast through the Barents Sea and north over Kvitoya. The low 
pressure system then moved into the central Arctic basin where it slowly migrated in an 
erratic westward track to northwest Greenland and dissipated. This cyclone track for 9 



48 



October is typical of both the winter and summer cyclone track for this region from 
Serreze and Barry (1988) and is depicted in Gorshkov's (1983) September through Jan- 
uary tracks as presented in Chapter II. Except for the cyclogenesis that occurred over 
the RjV Polarbjoern on the 12th, October's cyclones stayed south of 75°N. This cor- 
relates very well with climate studies which depict cyclones tracking northeast through 
the Norwegian Sea and then east through the southern Barents Sea. The strengthening 
circumpolar vortex during the fall to its winter maximum steers cyclones south of the 
central Arctic basin and south of 75°N. 

The cyclone on 2 December tracked from northeast Greenland southeast 
across the Greenland Sea, Fram Strait, Svalbard, then southeast to Novaya Zemlya. 
This trajectory is very similar to The climatic cyclone track for January and February 
as depicted by Gorshkov (1983) in Fig. 10c and d. On 8 December, a cyclone originat- 
ing from southeast Greenland tracked northeast into the Greenland Sea and then to 
Svalbard. From Svalbard, the cyclone moved into the Arctic basin where it stagnated 
and filled. This trajectory is well documented by Serreze and Barry (1988) and Gorshkov 
(1983) as being a major cyclone track. Similar to the cyclone on 2 December, the 
cyclone on 2 January 1989 tracked from northeast Greenland southeast over Svalbard 
and to Novaya Zemlya. This track mirrors the climate cyclone track for January and 
February depicted in Gorshkov (1983) Fig. 10c and d. 

Only two of the five cyclones (9 October and 8 December) moved into the cen- 
tral Arctic basin as depicted in the Serreze and Barry climate study of the Arctic. Two 
of the storms (2 December and 2 January) entered the Arctic basin above 80°N but then 
tracked southeast to Novaya Zemlya. The cyclone on 12 October entered the Arctic 
basin for several days but then tracked southeast to Novaya Zemlya similar to the 
cyclones on 2 December and 2 January. One cyclone on 20 September tracked opposite 
of the other cyclones, out of the central Arctic basin and then southeast to Novaya 
Zemlya. 

The synoptic patterns that occurred during Phase I correlate very well with the 
surface pressure patterns and cyclone trajectories described by Gorshkov (1983) and il- 
lustrated in Fig. lla-c. These are Gorshkov's autumn-winter synoptic patterns that 
persist 40% of the time in the fall and early winter. Other patterns (Fig. 1 ld-f) did occur 
but less than 20% of the time in agreement with Gorshkov (1983). 



49 



C. TEMPERATURE INVERSIONS 

Vertical profiles of potential temperature, potential dewpoint, and wind speed and 
direction were obtained from R/V Polarbjoern rawinsonde launches and were analyzed 
with regard to inversion properties. Inversions were identified in greater than 95% of 
the rawinsonde profiles. The temperature inversions were studied and compared to the 
climatology of the region. Results are summarized in Table 2 according to percent of 
inversion cases. An example of each inversion type during Phase I is illustrated in 
Fig. 36. The multiple inversion, mixed layer below inversion, and stable layer below 
inversion types represent upper level inversions. An interesting outcome of this data set 
is that the results differ significantly from those found by Vowinckel and Orvig (1970) 
which were described in Chapter II, Section A.4. Their findings for surface and upper 
level inversions are summarized in Table 3. 

Table 2. INVERSION TYPE AND FREQUENCY DURING PHASE I 



Month 


Surface-based 
Inversions (%) 


Multiple 
Inversions (%) 


Mixed Layer 
Below Inver- 
sion (%) 


Stable Layer 
Below Inver- 
sion (%) 


September 


20 


30 


40 


10 


October 


24 


25 


56 


4 


November 


22 


7 


53 


15 


December 


21 


21 


31 


16 



Table 3. FREQUENCY OF INVERSIONS 
VOWINCKEL AND ORVIG DATA 



SUMMARIZED FROM 



Month 


Surface Inversion 
(%) 


Upper Level 
Inversion (%) 


September 


38 


42 


October 


55 


40 


November 


78 


17 


December 


72 


25 



The incident of surface-based inversions did not occur nearly as often in this study 
as reported by Vowinckel and Orvig (1970). An increase percentage of surface inversions 
toward winter did not occur as noted in their study. From October to December, the 



50 



SPECIFIC HUMIDITY C/KC 



10000 
*000 

(ooo 

7000 

* tooo 

tel 

=> booc 

< 4000 
JOOO 
7000 

tooo 





1 




1 




i 






J 




4 




































































, 






























\ 




















\ 




, 














\ 




•' 
















w 


V 


-' •/ 


















I 



















-40 -io -jo -to o io jo jo 40 io tc 
POTENTIAL TEMPERATURE °C 

5 NOV 1989 1100 GMT POLARBJOLRN 

n a 

LAT 80°47'N LONC 35°14'E 

SPECIFIC HUMIDITY 6/KC 

12 3 4 



10000 
JOOO 

tooo 

7000 
(000 
SOOO 
4000 
JOOO 
7000 
1000 







-40 -10 -20 -10 10 20 JO 40 SO (0 

POTENTIAL TEMPERATURE °C 

14 DEC 1989 1055 GMT POLARBJOERN 

c 
LAT 78°47'N LONG 31° 30'F. 



10000 

tooo 
sooo 

7000 
(000 

sooo 

4000 
JOOO 
2000 
1000 









SPECIFIC HUMIDITr C/KC 

1 2 J 




4 






























































\ 












/ 


















• J 










\ 








/ 














\ 






i 














1 


i_ 




' 
















L 


/ 



































-40 -JO -20 -10 10 20 JO 40 SO (0 

POTENTIAL TEMPERATURE °C 
1 DEC 1989 2240 GMT POLARBJOERN 
LAT 79°53 / N LONG 31 C 1J'E 



10000 

sooo 
sooo 

7000 
(000 

sooo 

4000 
JOOO 
7000 
1000 




D 




SPECIFIC HUMIDITY C/KC 
1 2 J 




4 




















1 






















\ 












' 




























\ 








.' 












\ 
( 




















" 1 


\\ 




















I 




/. 














' 


\ 


\ , 


















7- 



















-40 -JO -20 -10 10 20 JO 40 SO 

POTENTIAL TEMPERATURE °C 
23 NOV 1989 1040 GMT POLARBJOERN 

LAT 80°M'N LONG 31°2'E 



Fig. 36. Examples of Inversion Types during CEAREX: (a) surface inversion; (b) 
multiple inversion; (c) stable layer below inversion; and (d) well mixed 
layer below inversion. 

upper level inversions dominated surface inversions by a factor of four. This is in sharp 
contrast to Vowinckel and Orvig results which found that the percentage frequency of 



51 



surface and upper level inversion were nearly the same in October. Then the percentage 
frequency of surface inversions increase relatively during the fall until December when 
the percentage frequency of surface inversion is three times that of the upper level inv- 
ersions. 

November and December are the months most inconsistent with their study. This 
could be accounted for by several different factors. The R/ V Polarbjoern was not located 
over the central Arctic basin as the study's results were. The Rj V Polarbjoern was in- 
stead located on the eastern side of Svalbard on an ice flow that was moving south and 
in close proximity to the MIZ and the open ocean. The second factor is that two 
cyclones tracking through the region in December are an unusual occurrence for central 
pack ice and this could be an important factor in the small percentage of the surface- 
based inversion frequency for December. The strong winds and warm air advection 
could destroy surface-based inversions. Typically, a very large and stable pool of air sits 
over the central Arctic basin which accounts for the large number of surface-based inv- 
ersions that should occur. East of Svalbard, a very strong surface temperature gradient 
is present as discussed in Chapter II and any moderate winds could easily advect warmer 
air into the region near the MIZ potentially destroying a surface inversion. 

The next chapter will present two case studies. The first case study covers the in- 
tense storm that occurred over the RjV Polarbjoern on 12 October 1988. The second 
case study deals will a boundary layer front that formed in Fram Strait on 10 October 
1988 and later evolved into a polar low. 



52 



IV. CASE STUDIES 

Results from analyses of two meteorological events are presented in this chapter. 
In the first case study, cyclogenesis over the R/V Polarbjoern on 12 October is compared 
with different cyclones tracks over the eastern Arctic ocean from September to January. 
Although there are only a small number of reporting land stations in the vicinity of the 
R/V Polarbjoern, the deployed drifting buoys and the available satellite imagery allowed 
the detection of cyclogenesis in the region. Cyclogenesis over the pack ice northeast of 
Svalbard is an unusual occurrence and not depicted in Arctic climate studies. 

The second case study described a boundary layer front and polar low development 
and was selected to compare with studies conducted during MIZEX experiments and the 
Arctic Cyclone Expedition. Experiments were not being conducted in Fram Strait dur- 
ing the second case study, but satellite imagery available for the drift phase of CEAREX 
provided the necessary information for analyzing the boundary' layer front and its evo- 
lution into a polar low on 10 October in Fram Strait. Fett (1990) assisted in the inter- 
pretation of cloud features and streamline analysis in the satellite imagery for both 
studies. 

A. CYCLOGENESIS EVENT OVER R/V POLARBJOERN (12 OCTOBER 1988) 

Mesoscale analysis of the meteorological conditions will be presented for the region 
between Svalbard and Franz Joseph Land. Redrawn surface analyses were made using 
surface data from deployed buoys, observations from the R/ V Polarbjoern, land and ship 
observations, satellite imagery, and NMC and NOGAPS global surface analyses. The 
times of the DMSP mosaics represent the swath closest to Svalbard. 

1. Cyclogenesis Event 

The DMSP satellite mosaic for 1 12320 UTC October ( Fig. 37) suggests a low 
level frontal zone extending south from the Arctic basin north of Svalbard then south- 
west over the Norwegian Sea. This surface frontal zone is also depicted on the NMC 
hand analyzed surface analysis for 120000 UTC. The NMC (not shown) surface analysis 
shows low level circulation north of Svalbard which is not evident on satellite imagery. 
Surface stations in the vicinity are reporting convective activity with rain and snow 
showers along the frontal zone. The NOGAPS 500 mb analysis for 120000 UTC 
(Fig. 38) shows a short wave trough extending south over Fram Strait and the 
Norwegian Sea. 



53 




Fig. 37. DMSP satellite mosaic for 1 12320 UTC October 1988: A denotes the 
location of Spitzbergen, B is Northeast Land and C is Franz Joseph Land. 



54 




Fig. 38. NOGAPS 500 mb analysis for 120000 UTC October 1988 

On the DMSP satellite mosaic at 120828 UTC ( Fig. 39) and NOAA-10 satellite 
image at 121012 UTC October (Fig. 40) the formation of a "baroclinic leaf cloud pat- 
tern is evident north and east of Svalbard. The "leaf is oriented north-south in the 
DMSP mosaic (Fig. 39) and located on the forward side of the 500 mb trough located 
in Fram Strait. Less than two hours later the "baroclinic leaf cloud pattern (Fig. 40) 
has rotated slightly counterclockwise as described by Weldon (1979). The ragged edges 
at the northeast end are readily seen as well as the presence of low clouds at the tail end. 
Upper level cloudiness southeast of the 500 mb jet is present as was the case on the ex- 
ample of a "baroclinic leaf in a high amplitude trough (Fig. 14) presented in Chapter 
II. Any low level development at this time is obscured by the high level clouds. 



55 




Fig. 39. DMSP satellite mosaic at 120828 UTC October 1988 



56 




..»->. I ' *r onffi'-'^ wQf . n \r> t-acoz <<"- o -• <r . «:■ 






Fig. 40. NOAA-10 satellite image for 121012 UTC October 1988 

NOGAPS 500 mb analysis for 121200 UTC (Fig. 41 on page 58) depicts a low 
height center over northern Greenland with a troughing extending southeast then south 
over Fram Strait and the Norwegian Sea. Maximum 500 mb winds lie upstream of the 



57 



"baroclinic leaf in confluent flow. Decreasing winds in difluent flow are downstream 
of the cloud pattern (Fig. 41). NOGAPS 850 mb analysis (not shown) shows moderate 
warm air advection at 111200 UTC with strong warm air advection occurring from 
120000 UTC through 121200 UTC. Surface reports from 120000 UTC to 121200 UTC 
indicate continued convective activity along the surface frontal zone. Snow is falling at 
the Rj V Polarbjoern which is located directly under the "leaf system. 




Fig. 41. NOGAPS 500 mb analysis for 121200 UTC October 1988 

The positions of the buoys and the RjV Polarbjoern for October 10th and 20th 
are shown in (Fig. 42). Time series of temperature and pressure for each buoy are pre- 
sented in Fig. 43. Between 111800 UTC and 120000 UTC, the three southernmost 
drifting buoys (Fig. 43b) experience sharply rising temperatures which reach their peak 
between 06 UTC and 18 UTC on the 12th in the strong low level warm advection from 
the south. Buoy number four, located furthest west, showed a 10°C lower temperature 
minimum than the other buoys except for buoy number one which has a difference of 
5°C. The three northernmost buoys (Fig. 43a) reached their temperature maximum at 



58 



a later time, between 1200 UTC and 1800 UTC on the 12th, except for buoy number 
one. This buoy, located farthest northwest over the ice pack, reached its maximum 
temperature at 06 UTC and was 5°C colder than all the buoys except for buoy number 
four, also located on the western side of the buoy array. 



1010 + 
1020 x 



• j'jo 




lo'l 22' £ J«'E *« E 



Fig. 42. R/V Polarbjoern and buoy positions for October 1988 



59 








A"\ 




■ 




^/^V. /7 


— xj"' 


£ 


bf* 




:■ V 




*~v 


• 




00 06 O 16 
OCTOBER II 



00 04 12 IS 
OCTOBER Q 
8U0TV 1 (UNO 2 (DASH) 3 (LINE/DOT) 



00 0« 12 IS 

OCTOBER U 



00 06 12 18 
OCTOBER 11 



00 08 12 M 00 08 12 IS 
OCTOBER C OCTOBER IJ 

BUOrS: 4 (UNO 5 {DASH} « (LRC/DOT) 



Fig. 43. Pressure and temperature time series for drifting buoys 

Low level cyclonic circulation becomes evident on the 121200 UTC October re- 
drawn surface analysis (Fig. 44). At 121500 UTC, surface pressures are still falling at 
the drifting buoy positions and at the ship. Winds at the ship indicate that the low 
pressure center is forming southwest of the ship. Temperatures at all buoy locations and 
at the ship are still increasing at this time. 



60 




Fig. 44. Surface analysis for 121200 UTC October 1988 

Winds at the Rj V Polarbjoern back from southwest to northwest and increase 
from 8 to 20 mr 1 from 1500 UTC to 1800 UTC. The ship's time series plot from 10 to 
17 October (Fig. 45) illustrate this sharp wind shift, both in direction and speed. Tem- 
peratures at the ship and the buoy locations begin to sharply decrease in the low level 
cold air advection from strong northwesterly winds. The cyclone deepens from 975 mb 
to 967mb from 121200 UTC to 121800 UTC. The surface analysis at 121800 UTC 
(Fig. 46) shows the cyclone position northeast of the ship and the resulting surface wind 
field. Snow is falling heavily at the ship and convective activity continues to occur in the 
frontal zone. The surface low pressure system is not discernable on the DMSP satellite 
mosaic at 122310 UTC due to the presence of the high level cloudiness. 



61 




Fig. 45. Time series of observations for R/V Polarbjoern (10-17 October) (from 
Lackman et al. 1989) 




Fig. 46. Surface analysis for 121800 UTC October 1988 



62 



NOGAPS 500 mb analysis at 130000 LTC October shows a 5903 m low height 
center north of 80°\ between Svalbard and Franz Joseph Land (Fig. 47). At this time 
NOGAPS analyses at 500, 700, and 850 mb, and the surface indicate that the cyclone is 
now fully vertically-developed. The redrawn surface analysis at 130000 LTC October 
(Fig. 48) positions the cyclone north of the NOGAPS surface analysis. 



, 7 

l 



/ 







■ 500 MB B8101300Z . 



Fig. 47. NOGAPS 500 mb analysis at 130000 UTC October 1988 



63 




Fig. 48. Surface analysis at 130000 UTC October 1988 

The low pressure system remains steady at 967 mb and quasi-stationary north- 
east of the R/V Polarbjoern from 121800 UTC to 131200 UTC. By 131800, the cyclone 
drifts slowly south, east-northeast of the ship and the central pressure begins to rise as 
depicted on the 131800 UTC surface analysis (Fig. 49). The pressure at the ship was 
considered too low and was disregarded. The ship's surface pressure was consistently 
lower than the array of buoys throughout the experiment. At this time, the surface 
buoys were reporting surface pressures of 974 to 978 mb. NOAA-10 satellite image at 
130950 UTC (Fig. 50) shows a well developed comma shaped cloud pattern located 
northeast of Northeast Land. A clear cold dry slot of air is beginning to wrap around 
the vertically developed low pressure system. 



64 




Fig. 49. Surface analysis for 131800 UTC October 1988 



65 




x ' *r o u, in -> *- — o t - <ft >*i t- u. o r •*"' o — 'ii •:<;< &•■ . «-■ -• • ~ f 



Fig. 50. NOAA-10 satellite image at 130950 UTC October 1988 



66 



NOG APS 500 mb analysis shows a low height center over Franz Joseph Land 
at 131200 UTC (Fig. 51). The low height center remains quasi-stationary and slowly 
starts to fill as indicated by rising surface pressures from 131800 UTC to 140000 UTC 
(not shown). 

DMSP satellite mosaic at 132240 UTC (Fig. 52) shows cloud bands beginning 
to weaken and become disorganized as the cold air is being entrained into the center of 
the low pressure system. By 140749 UTC, DMSP mosaic (Fig. 53) suggest that the cold 
dry air that is being wrapped around the core of the low pressure system. The cyclone 
has tracked slowly east and is still filling. Winds at the ship decreased to below 10 ms~ x 
by 141800 UTC and precipitation ceased. 



MIS'- YK 




Fig. 51. NOG APS 500 mb analysis for 131200 UTC October 1988 



67 




Som - 30U)ff 20UI 



Fig. 52. DMSP satellite mosaic at 132240 UTC October 1988 



68 




Fig. 53. DMSP satellite mosaic at 140749 UTC October 1988 



69 



2. Summary and Conclusions 

The development of the cyclone on 12 October in a "baroclinic leaf cloud sys- 
tem was detected through satellite imagery. Cyclogenesis over the Arctic ice pack is not 
evident in most of the Arctic climate studies (Serreze and Barry 1988; Sater et al 1971; 
and Sechrist et al. 1989). This is undoubtably associated with lack of data. Only 
Gorshkov (1983) shows a cyclogenesis region over the Barents Sea in February which 
may or may not be ice covered. The track from this cyclogenesis region is southeast, 
which is the track the 12 October cyclone takes on the 14th and 15th of October to north 
U.S.S.R. Gorshkov also depicts cyclogenesis near the North Pole, over central pack ice 
with the cyclone then moving east as did the 13 October cyclone. 

The significant difference is October is that an anticyclone did not persist over 
the northern Arctic basin near the U.S.S.R. This accounts for the lower anomalous sea 
level pressures and low heights correlated for the month of October in that region. The 
500 mb geopotential heights and 1000-500 mb thickness charts illustrate the lower 
heights and colder temperatures than average for October. The lower heights and colder 
temperatures over the central Arctic and the higher heights over Greenland set up a 
stronger temperature and pressure pattern gradient in the vicinity of Svalbard, 
Norwegian and Barents Seas for October which led to higher than average cyclone ac- 
tivity. The significantly lower heights north of 80°N. between Svalbard and Franz 
Joseph Land, in combination with the weaker circumpolar vortex set up a strong 
baroclinic zone in the Barents Sea that supported vigorous cyclogenesis. The "baroclinic 
leaf represents an area where a baroclinic zone is forming or intensifying. This corre- 
lates well with the sharp temperature gradients in the vicinity of Svalbard where 
cyclogenesis occurred. 

Although the 12 October cyclone developed over the Arctic ice pack, the strong 
southerly winds in advance of the upper level trough over Fram Strait brought warm 
moist air to the vicinity of the ship. The warm moist air being advected into the region 
in combination with the cold pool of air moving south towards the ship over the pack 
ice, created a strong baroclinic zone formation as indicated by the presence of the 
"baroclinic leaf. A "baroclinic leaf does not always evolve into a well vertically devel- 
oped low pressure system and the resultant classic comma cloud (Weldon 1979). It is 
proposed that the availability of warm moist air from open water in the Barents Sea had 
the most influence on the rate of surface cyclogenesis. Although no rawinsondes were 
launched during the cyclogenesis event, temperature increases of 15 to 20 °C at the buoy 
and at the ship over a relatively short time period indicates the presence of a warm 



70 



maritime air mass which did not modify or lose much of it's moisture as it moved north 
over the ice pack. The 500 mb winds upstream were extremely strong. A strong low 
level front also existed with convective activity along its frontal position. The "leaf 
formed in a 500 mb trough moving slowly east across Greenland Sea and Fram Strait 
bring positive vorticity advection. Strong warm air advection from the surface to 850 
mb played a crucial role in stretching the column of air over the region producing up- 
ward motion and increased vorticity. Strong convective activity, which is unusual for 
the Arctic is occurring in the vicinity. 

Although the cyclogenesis on 12 October was an infrequent event, cloud pat- 
terns like the "baroclinic leaf can be indicative of much more dynamic conditions 
occuring than indicated by surface reports and global analyses. Especially in the Arctic, 
where data is sparse and the input to the models is much less abundant than at mid 
latitudes, cloud patterns must be closely studied. 

B. BOUNDARY LAYER FRONT AND POLAR LOW DEVELOPMENT 

1. Overview 

This section describes the formation on 10 October 1988 of what has interpreted 
to be a boundary layer front on which a polar low formed. The analysis is based pri- 
marily on satellite imagery' and NOGAPS upper level pressure, wind, and temperature 
fields. There are few land reporting stations on Svalbard and the northeast coast of 
Greenland, however, they are not sufficiently close to the formation location of the front 
for significant contribution. The front was clearly visible on DMSP and NOAA satellite 
imagery. 

NOGAPS 500 mb analysis at 100000 UTC October shows a 5775 meter low 
height center north of 80°N between Greenland and Svalbard. A deep trough extends 
southward over Fram Strait and into southern Norway. The low height center remains 
under constant pressure and moves westward, north of Greenland by 110000 UTC. A 
weaker upper level trough then becomes established over the east coast of Greenland. 
At 850 mb, warm air is being advected into Fram Strait from southwest winds over the 
Norwegian Sea. West-northwest flow from Greenland ice sheet and the Arctic ice pack 
is maintaining cold air flow into the Greenland Sea. 

2. Satellite Imagery and Streamline Analysis 

NOAA 10 satellite image at 100915 UTC (Fig. 54) shows a well defined line of 
convective activity in the Greenland Sea, east of the MIZ. Northerly flow turns 
anticyclonically in the northern portion of the neutral point then sharply cyclonic 



71 



around the northern edge of the boundary layer front. Winds from east Greenland are 
converging into the front and producing multiple vortices. A broad area of 
stratocumulus clouds are present in Fram Strait. Svalbard is reporting moderate 
southerly winds and lowering pressure as a small vortex is seen forming over 
Spitzbergen. 



72 




Fig. 54. NOAA 10 Satellite Image at 100915 UTC October 1988 



73 



NOAA 10 satellite image at 101056 UTC (Fig. 55) shows an enlarged view of 
the boundary layer front region. The sharp anticyclonic turning of the winds over Fram 
Strait is evident in the cloud streets in the image. The winds then become cyclonic 
converging with the cold dry winds from east Greenland. Streamline analysis depicts a 
broad area of stratocumulus clouds present under strong divergent flow. 

By 101307 UTC (Fig. 56), NOAA satellite image shows the ice edge boundary 
layer front north and east of its previous position. Low level cumuliform clouds are 
turning cyclonically at the northern edge of the layer front. Converging streamlines are 
analyzed along the thin band of convective clouds as seen in (Fig. 56). Stratocumulus 
clouds are maintained between Spitzbergen and the boundary layer front under divergent 
flow. Spitzbergen reported 10 msr 1 of westerly wind at 1200 UTC as the northerly winds 
west of Spitzbergen turn sharply cyclonic around Svalbard. Winds along the east coast 
of Greenland are reported as west or southwest during this time. 



74 




Fig. 55. NOAA 10 satellite image at 101056 UTC October 1988 



75 




Fig. 56. NOAA 10 satellite image at 101307 UTC October 1988 



76 



The next available satellite mosaic was at 102350 UTC (Fig. 57), ten hours later 
to the previous, shows a polar low west of Spitzbergen at the northern end of the 
boundary layer front. The low clouds become tightly banded into the center of the 
vortex. The thin band of convective activity along the front is now oriented to the 
southeast and extends south of Spitzbergen. Spitzbergen is reporting southerly winds 
at 27 knots and lowering pressure in approach of the polar low and the boundary layer 
front. Strong northwest winds are indicated by the clouds streets in east Greenland Sea 
behind the front and polar low. At 110853 UTC (not shown) satellite imagery shows 
that the polar low and boundary layer front have dissipated. The entire event lasted less 
than 24 hours. 



77 




Fig. 57. DMSP satellite image at 102318 UTC October 1988 



78 



3. Comparison v>ith Other Studies 

This ice-edge boundary layer front formation differs from previously described 
studies of boundary' layer fronts. Fett (1989b) study of a boundary layer front formed 
with colder air to the east and warmer modified air to the west. In this case, colder air 
was to the west and warmer air was to the east. The boundary layer front formed with 
the outbreak of cold air from the ice pack that flowed southward over Fram Strait. The 
warm tongue of water in Fram Strait, a branch of the Norway Current, modified the cold 
air from off the ice regions. This modified relatively warm and moist air meets the un- 
modified cold air flowing east from the Greenland ice sheet. This front was found farther 
north than previous case studies and in a different season. Shapiro and Fedor (1989) 
and Fett (1989b) observed boundary layer fronts in the winter, from December through 
March, rather than the fall. 

The major difference between this front and the boundary layer front described 
by Fett (1989b) and Shultz (1987) is that this front formed under a low-level trough that 
moved northeast with this upper level flow. Maximum vorticity occurred at the northern 
boundary of the front as evidenced by the multiple large vortices visible along the 
northern portion of the front on satellite imager}'. The large amount of vorticity con- 
centrated at the northern boundary of the front accounts for the subsequent formation 
of a polar low at that location. Fett (1989b) and Shultz (1987) case study involved the 
formation of boundary layer front that propagated westward in an easterly wave. The 
vorticity in this inverted trough was centered at the southern end of the boundary layer 
front as evidenced by the presence of strong vortices shown in satellite imagery. Al- 
though a polar low did not form from this boundary layer front in an easterly wave, 
other cases by Fett (1989b) involved polar low development on the southern portion of 
boundary layer fronts. 

A polar low formed with this ice-edge boundary layer front. Fett (1989b) pro- 
poses that boundary layer fronts can evolve into polar lows only if cold air aloft and a 
500 mb trough or low height center are present. As presented in the overview of this 
section, NOGAPS 500 and 850 mb analyses depict a deep upper level trough and cold 
advection into the East Greenland Sea. This upper level support and strong baroclinic 
zone at the surface together with the ice-edge boundary layer front provided for the de- 
velopment of a polar low. 



79 



V. SUMMARY AND RECOMMENDATIONS 

A. SUMMARY 

The drift phase of CEAREX was dominated by short periods of frequent cyclone 
activity followed by long periods of high pressure ridging over the Eastern Arctic from 
Greenland or northern Europe. Winds were predominately from the north-northwest 
which steered the ship east of Spitzbergen and Kvitoya as it drifted within the southward 
advancing Arctic pack ice. 

On 12 October 1988, strong cyclogenesis occurred over the drift ship. This is an 
infrequent event over Arctic ice due to the presence of a layer of very stable, cold, and 
dry air over the surface and the absence of any strong baroclinicity. The ship's position 
was close the MIZ and was under the influence of warm air advection from the surface 
to 850 mb coming from the warm waters of the Norwegian Sea. This warm moist air 
being advected in the region in combination with an upper level trough provided a 
strong baroclinic zone which was evident in a "baroclinic leaf that was observed in 
satellite imagery. The "leafs" subsequent vertical development and intense cyclogenesis 
at the surface was tracked by surface observations. Data from the research ship and the 
six drifting buoys proved invaluable to the reconstruction and analysis of this 
cyclogenesis event. 

On 10 October 1988, a boundary layer front was observed in the east Greenland Sea 
by satellite imagery. The front formed between a cold dry air mass flowing east from the 
Greenland continent and affixed ice sheet, and a relatively warm moist air mass to the 
east that was initially cold air flowing south from the Arctic ice pack which became 
modified over the warm waters of Fram Strait, west of Spitzbergen. Vortices on the 
northern end of the boundary layer front subsequently developed into a polar low that 
was seen on satellite imagery several hours later. The polar low formed in Fram Strait 
and then moved east-southeast toward Spitzbergen where it dissipated. The boundary 
layer front in this study is quite different than those noted by Shultz (1987), Fett (1989b), 
and Shapiro and Fedor (1989). A major difference noted that this front was moving 
eastward, not stationary or moving westward as noted by the previous cases. In addi- 
tion, the polar low formed at the northern rather than the southern end of the front. 
The use of satellite imagery proved crucial to this analysis as no ship or buoys were re- 
porting in this area. 



80 



Other than these two events, the synoptic conditions during the drift phase are well 
represented in the climate study presented by Gorshkov (1983). Gorshkov's frequency 
of occurrence of cyclonic activity in the Eastern Arctic is much higher than Serreze and 
Barry (1988) and coincided with this study's findings. 

B. RECOMMENDATIONS 

The detection of the cyclogenesis over pack ice was possible because of the research 
ship and the array of drifting buoys. A permanent and widespread array of drifting 
buoys are required to monitor the meteorological conditions in the Arctic. 

A more detailed understanding of the formation of boundary layer fronts and their 
subsequent development into polar lows require surface and upper air observations in 
the area in addition to satellite imagery. Further studies of the phenomena described 
require in situ measurements. The use of drifting buoys and additional ship and aircraft 
measurements are necessary to further document and understand these phenomena. 

Satellite imagery still remains the forecaster's primary tool for detecting rapid de- 
veloping Arctic storms and observing mesoscale features like boundary layer fronts and 
polar lows. Any gap of satellite imagery can cause an incorrect analysis or omission of 
a meteorological event. Training on interpreting satellite imagery' is essential to ex- 
ploiting the full potential of satellite images in the Arctic. The forecaster must have a 
basic knowledge of cloud patterns and associated meteorological features in the atmos- 
phere. A thorough knowledge of the physical processes indigenous to the Arctic is the 
key to successful analyses in this unique area of the world. 



81 



LIST OF REFERENCES 

Bader, M.J., K.A. Browning, G.S. Forbes, V.J. Oliver, and T.W. Schlatter, 1988: To- 
wards improved subjective interpretation of satellite and radar imagery in weather 
forecasting: results of a workshop. Bull. Amer. Met. Soc, 69, 764-769. 

Businger, S., and R. J. Reed, 1989: Polar Lows. In Polar and Arctic Lows, P.F. Twitchell, 
E.A. Rasmussen, and K.L. Davidson (Eds), A. Deepak Publishing, Hampton, VA, 

3-45. 

Climate Analysis Center, 1988a: Climate Diagnostics Bulletic, September 1988, near 
real-time analyses, ocean/atmosphere, No. 88/9. Prepared by U.S. Department 
of Commerce, Washington, D.C., 37 pp. 

, 1988b: Climate Diagnostics Bulletic, October 1988, near real-time analyses, 

ocean/atmosphere, No. 88/10. Prepared by U.S. Department of Commerce, 
Washington, D.C., 38 pp. 



, 1988c: Climate Diagnostics Bulletic, November 1988, near real-time analyses, 

ocean/atmosphere, No. 88/11. Prepared by U.S. Department of Commerce, 
Washington, D.C., 48 pp. 



, 1988d: Climate Diagnostics Bulletic, December 1988, near real-time analyses, 



ocean/atmosphere, No. 88/12. Prepared by U.S. Department of Commerce, 
Washington, D.C., 43 pp. 

, 1989: Climate Diagnostics Bulletic, January 1988, near real-time analyses, 



ocean/atmosphere, No. 89/1. Prepared by U.S. Department of Commerce, 
Washington, D.C., 48 pp. 

Ebert, E.E., 1989: Analysis of polar clouds from satellite imagery using pattern recogni- 
tion and a statistical cloud analysis scheme. J. Appl. Met., 28, 382-399. 



82 



Fett, R.W., 1989a: Navy Tactical Appl. Guide, Vol. 8, Arctic Weather Analysis and 
Forecast Applications, NEPRF Technical Report 89-07, Naval Environmental Pre- 
diction Research Facility, Monterey, CA, 364 pp. 

, 1989b: Polar development associated with boundary layer fronts in the 



Greenland, Norwedian, and Barents Sea. In Polar and Arctic Lows, P.F. Twitchell, 
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, 1990: Personal Communication. 



Gorshkov, S.G., 1983: World Ocean Atlas Vol. 3 Arctic Ocean. Pergamon Press, 184 pp. 

Lackman, G. M., P. S. Guest, K. L. Davidson, R. J. Link and J. Gonzalex, 1989: 
CEAREXl Polarbjorn Meteorological Atlas. Naval Postgraduate School, Monterey, 
CA, 545 pp. 

Lystad, M. (Ed.), 1986: Polar Lows in the Norwegian, Greenland and Barents Sea. Final 
Rep., Polar Lows Project, The Norwegian Meteorological Institute, Oslo, Norway, 
196 pp. 

National Science Foundation, 1987: Arctic Research of the United States, Volume 1. 
Prepared by the Interagency Arctic Research Policy Committee, Washington, DC, 
121 pp. 

, 1988: Arctic Research of the United States, Volume 2. Prepared by the Inter- 



agency Arctic Research Policy Committee, Washington, DC, 102 pp. 

Phegley, L.D., 1985: Synoptic/ Mesoscale Meteorology Features in the Marginal Ice Zone. 
M.S. Thesis, Naval Postgraduate School, Monterey, CA, 92 pp. 

Rao, P.K., S.J. Holmes, R.K. Anderson, J.S. Winston, and P.E. Lehr, 1990: Weather 
Satellites: systems, data, and environmental applications. American Meteorological 
Society, Boston, MA, 503 pp. 



83 



Rasmussen, E.A., 1989: A comparative study of tropical cyclones and polar lows. In 
Polar and Arctic Lows, P.F. Twitchell, E.A. Rasmussen, and K.L. Davidson (Eds), 
A. Deepak Publishing, Hampton, VA, 47-80. 

Sater, J.E., A.G. Ronhovde, And L.C. van Allen, 1971: Arctic Environment and Re- 
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Schultz, R.R., 1987: Meteorological Features During the Marginal Ice Zone Experiment 
from 20 March to 10 April 1987. M.S. Thesis, Naval Postgraduate School, 
Monterey, CA, 85 pp. 

Sechrist, F. S., R. W. Fett and D. C. Perryman, 1989: Forecasters Handbook for the 
Arctic. Draft Rep., T.R. 89-10. Naval Environmental Prediction Research Facility, 
Monterey, CA, 346 pp. 

Serreze, M.C., and R.G. Barry, 1988: Synoptic activity in the arctic basin, 1979-85. J. 
Climate, 1, 1276-1295. 

Shapiro, M.A., and L.S. Fedor, 1989: A case study of an ice-edge boundary layer front 
and polar low development over the Norwegian and and Barents Seas. In Polar and 
Arctic Lows, P.F. Twitchell, E.A. Rasmussen, and K.L. Davidson (Eds), A. Deepak 
Publishing, Hampton, VA, 257-277. 

Stringer, W.J., D.G. Barnett, R.H. Godin, 1984: Handbook for Sea Ice Analysis and 
Forecasting, CR 84-03. Naval Environmental Prediction Research Facility, 
Monterey, CA. 

Tchernia, P., 1980: Descriptive Regional Oceanography. Pergamon Press, Oxford, En- 
gland, 253 pp. 

Vowinckel, E., and S. Orvig, 1970: The climate of the North Polar basin, In: World 
Survey of Climatology: Volume 14, Climates of the Polar Regions, Amsterdam, 
Elsevier, 129-252. 



84 



Walsh, J.E. and W.L. Chapman, 1990: Short-term climatic variability of the Arctic. J. 
Climate, 3, 237-250. 

Weldon, R. 1979: Satellite Training Course Notes, Part IV, Cloud Patterns and the Upper 
Air Wind Field. Applications Division, National Environmental Satellite Service, 
NOAA, Washinton, DC, 79 pp. 

, 1986a: An oceanic cyclogenesis - its cloud pattern interpretation. In 



Meteorological Monographs: satellite imagery interpretation for forecasters. Vol. I, 
general interpretation synoptic analysis, P. S. Parke (Ed.), The National Weather 
Association, Temple Hills, MD, 2-G-l to 2-G-ll. 

, 1986b: Synoptic scale cloud systems. In Meteorological Monographs: satellite 



imagery interpretation for forecasters, Vol. I, general interpretation synoptic analysis, 
P. S. Parke (Ed.), The National Weather Association, Temple Hills, MD, 2-A-l to 

2-A-35. 

Zumberge, J.H., 1986: Introduction. Oceanus, 29, 2-8. 



85 



INITIAL DISTRIBUTION LIST 

No. Copies 

1. Defense Technical Information Center 2 
Cameron Station 

Alexandria, VA 22304-6145 

2. Library, Code 52 2 
Naval Postgraduate School 

Monterey, CA 93943-5002 

3. Chairman (Code MR/Hy) 1 
Department of Meteorology 

Naval Postgraduate School 
Monterey. CA 93943-5000 

4. Professor Kenneth L. Davidson (Code MR/Ds) 1 
Department of Meteorology 

Naval Postgraduate School 
Monterey, CA 93943-5000 

5. Professor Carlyle H. Wash (Code MR/Wx) 1 
Department of Meteorology 

Naval Postgraduate School 
Monterey, CA 93943-5000 

6. LT Stephanie W. Hamilton, USN 1 
Officer in Charge 

Naval Oceanography Command Detachment Adak AK 
FPO Seattle, WA 98791-2943 

7. Commander 1 
Naval Oceanography Command 

Stennis Space Center 
MS 39529-5000 

8. Director 1 
Naval Oceanographic and Atmospheric 

Research Laboratory 
Monterey, CA 93943-5006 



86 



9. Mr. Robert W. Fett 

Naval Oceanographic and Atmospheric 
Research Laboratory 
Monterey, CA 93943-5006 

10. Chief of Naval Research 
800 North Quincy Street 
Arlington, VA 22217 

11. Dr. Tom Curtin (Code 1 125AR) 
Office of Naval Research 

800 North Quincy Street 
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12. Dr. J. E. Overland 

Pacific Marine Environmental Laboratory 

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Administration 

7600 Sandpoint Way, NE 

Seattle, WA 98115 

13. Commanding Officer 

Naval Polar Oceanography Center 

Suitland 

Washington, DC 20373 



87 



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from 17 September 1988 to 
7 January 1989.